Nitric oxide and the non-adrenergic non-cholinergic neurotransmission

Camp Rwchem. Physical. Vul. llBA, No. 4, pp. 925-937, 1997 CopyrIght 8 1997 Elsevier Science Inc. All rights reserved.

ISSN @3@0-9629/97/$17.00 I’ll SO3170-9629(97)000?2-4

ELSEVIER

Nitric Oxide and the Non-Adrenergic NonCholinergic Neurotransmission G . E. Boeckxstaens * and I’. A. Pelckmansi_ *DIVISION OF GASTROENTEROLOGY,ACADEMIC MEDICAL CENTER, MEIBERCDREEF9, 1105 AZ, AMSTERDAM, THE NETHERLANDSAND ?DrvrsroN OF GASTROENTEROLOGY, UNIVERSITYHOSPITAL OF ANTWERP, WILRIJKSTRAAT 10. 2650 ANTWERP-EI)E~:EM,BEL(:ILIM

ABSTRACT. In the early 196Os, the first evidence in the presence adrenergic

of adrenergic

non-cholinergic

the discovery

of these

an d vasoactive substance

intestinal

released

transmitter.

hy these

By now,

interacting

4:925-937,

0

HISTORICAL about

autonomic

rabbit

responses

the nitrergic at pre- and/or

as follows:

after curari although

of which

nitric

accepted

“When

For

were example,

the vagus

given,

musculature

may be strong

as

How-

atropineshown

in

Langley

is stimulated

have been

of the whole

In

responses

atropine.

century,

stimulation

(28,132).

that

was considered

the functional

in a

. . there

of the cardia

contraction

in the

body of the stomach.” Thereafter, many other investigators demonstrated atropine-resistant inhibitory responses to vagal stimulation (104,150,153,169) or nicotine (9,lO). Until 30 years ago, these findings were explained by various theories.

Some authors

stimulation

parameters

stressed with

the importance

inhibition

simply

of non-

of physiologIca research

proposing

postsynaptic

events.

neurotransmitter,

the ongoing

nitric

the idea that

nervous Since

with

cm the nature

oxide

inhihitory

as putative

neurons

neun)-

release

COMF HIOCHEMPHYSIOI.

levels.

ATP of the more 1

18A;

oxide

of the

neurotransmitters.

by the alkaloid

and atropine there

range

as putative

theory

to support

with acetyl-cho-

innervation

to vagal tissue

Finally,

responses

of this part of the autonomic

a wide

proposed

mediated

of the ccjncept

Inc.

consisted

division

as respective

blocked

1s in fact relaxation region

system

at the end of the previous

gastrointestinal described

other

Science

mediating

candidates.

is reported

neurotransmission,

nervous

component

could be selectively resistant

with each

component

been

neurally

to the introduction

from “fatigue”

the parasympathetic

already

have

has generated

1997 Elsevier

and sympathetic

line and norepinephrine

ever,

systems

as main

evidence

30 years ago, it was classically

parasympathetic

the excitatory

organ substances

demonstrating

leading

The inhibitory

ASPECTS

the peripheral

general,

nerves

increasing

neurotransmitters, 1997.

several

polypeptide

KEY WORDS. NANC,

Until

in numerous

nerves,

was reported

antagonlsts,

neurotransmission.

has been illustrated

bystem

and cholinergic

of vagal resulting

Address repnnt requests to:G. E. Ik>eckxstaens. Academic Medical Center, University of Amsterdam. Divislan of Gastroenterology, Meihergdreef 9, 1105 AZ Amsterdam, The Netherlands. Tel. 31-20-5663632; Fax 31s20s 691703 3. Abhrwiatwn~+NO, nltrlc oxide; NOS, nitric oxide synthase; NANC, non-adrenergic non-cholmergic; VIP, vasoactive Intestinal polypptidr. Received 24 March 1996; accepted 28 May 1996.

(207). Others

tissue determined induced when

relaxation

when

of adrenergic

as an explanation

the tone

was high and excitation Alternatively,

the

fibers in the vagus was put forward

for the inhibitory

tion in the presence

of atropine

effect of vagal stimula-

(104,169).

early 196Os, with the introduction it became responses,

that the tone of the

such that vagal stimulation

was low ( 151,152,154).

the tone

presence

concluded

the response

However,

of anti-adrenergic

in the agents,

clear that comparable with the atropine-resistant there also existed so-called non-adrenergic effects

demonstrated independently by two groups. Martinson and co-workers suggested the presence of high-threshold inhibitory efferent effect “the

tibers

in the

by any adrenergic inhibitory

transmitter”

effect

seems

(147-150).

pig tenia

inhibitory coli

These

junction

ations

to

during

exerting

their

and concluded

that

to be mediated recording,

junction stimulation

potentials

transmural

nut

On the other

crose gap and intracellular demonstrated

vagal nerve, mechanism,

and

using the su-

Burnstock

potentials

et al. (59)

in the guinea

of its intrinsic the

stimulation,

hand,

by some other

nerves.

corresponding in

contraht

relaxto

those

evoked by stimulation of sympathetic nerve fibers, were not blocked by guanethidine and bretylium, leading to the conclusion that they “are mediated by intrinsic nerves which are different from the sympathetic and parasympathetic systems” (32,60,61). These series of experiments finally gave birth to the concept of non-adrenergic non-cholinergic (NANC)

neurotransmission.

By the

enJ

of the

196Os,

926

NANC nerves were recognized not only in the gastrointestinal tract of all vertebrates, including humans, but also in the urogenital, respiratory and cardiovascular systems (58).

PHYSIOLOGICAL IMPORTANCE @.strointestid Tract

Inhibitory NANC neurons have been demonstrated intramurally throughout the gastrointestinal tract and are now recognized to play an important role in the regulation of motility in all parts of the gut by mediating reflex patterns of physiological and pathophysiological relevance. During swallowing and food intake, the peristaltic motor activity of the esophagus provides proper transport of the swallowed bolus to the stomach. The peristaltic pressure wave in the body of the esophagus is preceded by a wave of inhibition, which also relaxes the lower esophageal sphincter and is known to be mediated by inhibitory NANC nerves (2,3,101,102). Recently, inhibition of artificially induced esophageal tone before the peristaltic wave was nicely illustrated in humans as well (185). Dysfunction of the inhibitory NANC nerves results in the motility disorder achalasia in the lower esophageal sphincter (37,202) and most likely in esophageal spasms or related primary motor disorders in the esophageal body (186,213). NANC-mediated relaxation of the stomach upon vagal stimulation was one of the first NANC responses described (3,147,148). The same pathway is responsible for the relaxation of the fundus upon food intake (the so-called receptive relaxation), increasing the reservoir capacity of the stomach and adjusting its tone to the amount of food swallowed (3,18,117). Similarly, infusion of nutrients in the intestine or distension of the antrum or duodenum relaxes the stomach via a reflex that is vagally mediated and involves inhibitory NANC neurons (1,4,19,76). The importance of the inhibitory NANC neurons to human gastric function is illustrated by increased gastric tone, impaired gastric reservoir function and decreased receptive relaxation after vagotomy (118,129,191,203). Vagotomized patients often complain of epigastric fullness and discomfort after meals, which might result from abnormal gastric receptive relaxation. Furthermore, NANC neurons also mediate the pronounced gastric relaxation associated with nausea and vomiting (2,5). The distal part of the stomach and the pylorus, both believed to regulate gastric emptying of solids, are shown to be under continuous inhibitory influence of NANC neurons. Stimulation of the inhibitory NANC neurons by transmural stimulation or vagal stimulation results in relaxation of the pyloric muscle (6,7,15). In infantile hypertrophic pyloric stenosis, absence of this inhibitory innervation at the pylorus most likely forms the basis of the outlet obstruction of the stomach in this disease (206). Moving further down the digestive tract, it is now recog-

G. E. Boeckxstaens and P. A. Pelckmans

nized that the inhibitory component of the peristaltic reflex, already described by Bayliss and Starling (28), is mediated by inhibitory NANC neurons (71), implying a fundamental role for normal aboral transport of digesta in small and large intestine. Not only in the stomach, but also in the small and large intestine, evidence is available indicating that the intrinsic inhibitory innervation is involved in the accommodation processes (65,86,208). The flow of ileal contents into the Iarge intestine and prevention of back flow is thought to be regulated by the ileocolonic junction, a region that also has a dense inhibitory NANC nerve supply (43,69,171). The bile flow, determined by coordinated motor activity of gallbladder and sphincter of Oddi, is also regulated by intrinsic inhibitory NANC neurons (29,30,33,83,172). Especially the sphincter of Oddi has a dense inhibitory NANC innervation that is tonically active. Transmural nerve stimulation and cholecystokinin activate these neurons, resulting in relaxation of the sphincter of Oddi, which contributes to the regulation of delivery of bile in the postprandial phase. Dysfunction of the inhibitory NANC nerves might be responsible for the elevated sphincter pressure recorded in patients with upper abdominal pain attacks due to sphincter of Oddi dyskinesia. Not only bile flow but also enzyme secretion by the pancreas is under control of NANC nerves (111,112,170). Finally, mechanical stimulation of the rectum elicits relaxation of the internal anal sphincter, a reflex that is crucial for normal defecation. It is mediated by intramural inhibitory NANC neurons to the smooth muscle cells of the sphincter (88,89,179). In Hirschsprung’s disease, this reflex is absent due to absence of these neurons, resulting in severe constipation (88).

Respiratory Tract

As in the gastrointestinal tract, neural control of the airways is more complex than initially thought and involves NANC mechanisms in addition to the classical adrenergic and cholinergic nerves (23). Airway NANC nerves were first demonstrated in isolated guinea pig trachea by electrical field stimulation; an initial contractile response was blocked by atropine, but the pronounced relaxation was only partly inhibited by adrenergic blockade, indicating that the major neural inhibitory pathway was non-adrenergic (67,68). The has been extensively deminhibitory NANC innervation onstrated in central and peripheral airways of animals and humans both in uivo and in vitro (78,131,141,180,194). In humans, bronchodilator NANC nerves are even believed to represent the only neural bronchodilator pathway (130). Vagal stimulation, referred to as preganglionic activation, produces NANC bronchodilation in oitro and in viva (66,156,180). There is, however, evidence suggesting that the NANC bronchodilating nerves are separate from the

NO as NANC Neurotransmitter

cholinergic

pathways

the vicinity

with

927

ganglia

of the esophagus

role in bronchodilation,

outside

(63,187).

the airways,

In addition

it is hypothesized

in

to its

tory pathway

innervation

tions,

from guinea

citatory

and inhibitory)

verging

effect

on

NANC

system

will set the tone of the airway to a predeter-

mined

level.

If tone

in relaxation,

where

tone

is lower than

point

is adjustable

adrenergic

pig that the NANC

(ex-

of the airways has a stabilizing meaning

is high,

that

activation

NANC

activation

as it will induce

contraction

the set point

(141).

mechanisms.

Whether

cies and is also true in eke,

will result when

the

by cholinergic

this applies

however,

and

to other

remains

spe-

the NANC

the only,

neural

bronchodilation

bronchodilator

is the main,

pathway

if not

in humans,

The

importance

blood

bital,

NANC

system

showing

may

be

decreased

NANC

responses

is still lacking

involved.

dys-

inhibitory

or

increased

in airways of asthmatic

however,

penis

and the anococcygeus

sess a powerful

NANC

of parasympathetic stration

sues, many

studies

transmitter

(95).

oxide

(NC)

reported

NANC

As discussed

as inhibitory

the “historical”

later,

NANC

are two that pos-

anatomically

importance

in vascular

Penile

erection

nous

outflow

corporal active

requires

(46,199)

and relaxation

sinusoids. by stimulating

produce

a vasorelaxant

the discovery

NANC

nerves

ral smooth ished

also markedly

muscle

cally elicited

Identification

with

relaxes

was first illus-

diabetes

of the inhibitory

muscle

nals; it should terminals;

and NANC

in the is to

of inhibitory strips of corpo-

cavernosum

impotence

tion

which

Interestingly,

of the corpus

oh-

and

released

importance

S)

innervation,

the most

concerned

the

by these inhibitory neurotransmitter(s)

for further

understanding

be released

electriis diminas such

system may contribute

process

stance

for uptake

should

have

a substance

be synthesized

from the nerve

to exogenous should should

applica-

mimic

parallel

such

putative on

as a

of the suh-

and drugs that effects

the re-

he an inactiva-

neurotransmitter,

to the exogenous

by the

in the nerve termi-

or redistribution

products

the responses

hased

mitters

there

for the proposed

nerve stimulation. in practice these tions

neurotransmitter

or its breakdown

transmitter

responses

stimulation;

mechanism

potentiate

it should

(Ca’+-dependent)

post-junctional to nerve

specific

as a neurotransmitter, criteria:

to the sites of storage

tion of the putative

ve-

of the sinusoids muscle

or he-

vasospasm

of research

of the inhibitory

is of course of extreme

and moved

to acetylcholine,

(113,175,181,182).

relaxation

in men

dysfunction

nerves.

neuron

decreased

subject

of the neurotransmitter

for nitric

stimulation

to the

of the NANC

identity

evidence

of this tissue to NANC

substance,

Conversely,

by hemolysate

NEUROTRANSMITTER(

and disputed

fulfill certain

(92,96,138,176),

the endothelium

for

may he in-

such as migraine.

vasodilation

NANC

be considered

of the smooth

In addition

by re-

with hemorrhages.

To

blood supply,

NANC

mechanism

vasodilation

may contribute

should

tis-

filling of the corpus cavernosum,

arterial

induces

and unaffected control

neural

headaches

of the NANC

sponses from increased

brain,

its neuro-

in these

physiology. resulting

artery

of physiology and pathophysiology and is absolutely necessary for development of new therapeutical approaches.

Since the demonsupply

neurotransmitter

muscle

of NO

regional

In the

to identify

nerve

were undertaken

in the anococcygeus

trating

innervation

origin (93,95,99,126).

of an inhibitory

muscle

with the genitalia

inhibitory

and penile

to tetrodotoxin

an alternative

tlow.

INHIBITORY

System

muscle tissues associated

regulation

excitatory

patients,

(24,141).

retractor

smooth

in the

of endothelium-derived

providing blood

intriguing The

endothelium

(17,46,50,135,143,197,198,209),

Since Urogenital

condi-

(14).

moval of the endothelium

served

evidence

ciliary

sensitive

blockade

bronchoconstrictor

Convincing

inhibi-

in pathological

urethra”

by production

pulmonary,

moglobin

of the

preced-

of this

is well established (157). In addition, evidence is accumulating that field stimulation of cerebral, mesenteric, infraor-

tively,

activity

be involved

of the

pressure

volved

increased

pressure

dysfunction

Blood Vessels

function of this system might contribute to the increased tone and hyperresponsiveness observed in asthma. Alternaan

may then

such as the “unstable

relaxation

to be deter-

mined. Because

in intraurethral

Theoretically,

conof the

The level of the set

and can be modulated

to the decrease

ing micturition.

from in vitro data

obtained

tone,

contribute

block

or

neuro-

respcmses

to

It should be emphasized, however, that criteria are rather empirical and expecta-

on experience

acetylcholine

with

the “classical”

neurotrans-

and norepinephrine.

So far, the inhibitory NANC neurotransmitter through three main phases. In 1970, Burnstock

has gone and col-

to the pathogenesis of some forms of impotence (175,182). The normal pattern of micturition is characterized by relaxation of the urinary outlet region and contraction of the

leagues (62) introduced the concept that ATP or a related nucleotide is released by the inhibitory NANC nerves. NANC nerve stimulation caused the release of ATP or its

urinary

breakdown

bladder

(detrusor

muscle).

NANC-mediated

relax-

ation has been demonstrated in human and animal trigone, bladder neck and urethra (8,12,13,124,125,190) and may

hibition NANC

products,

ATP caused tetrodotoxin-resistant

in-

of gut preparations previously shown to contain inhihitory nerves and nerve stimulation-induced re-

G. E. Boeckxstaens

928

laxation ATP

was similarly

affected

and quinidine

(62).

as ATP

These

by tachyphylaxis

results

and many

to

others

resulted in the purinergic theory put forward by Burnstock (55). In the following years, evidence in favor, but also against,

the

purinergic

theory

was reported

(57,94,136),

hydrophylic Da).

and P. A. Pelckmans

and has a small molecular

The

factor

is a potent

weight

vasodilator

(about

1000

in isolated

blood

vessels; it caused relaxation of isolated artery strips and a fall in pressure in vascular beds perfused with Krebs solution. However,

injected

intravenously

it had no effect

on blood

leading to the introduction of the peptidergic theory with the main candidate neurotransmitter vasoactive intestinal

pressure (47). As illustrated by in vitro studies, oxyhemoglobin was shown to block the relaxant effect of the inhibitory

polypeptide

factor

(VIP)

in cardiovascular ology opened

Finally,

spectacular

soon giving

NO

as

birth

inhibitory

discoveries

in endothelial

a new area of research,

(85,157,167,168) proposing

(80,103).

and more specifically

namely

physi-

and in addition

ated relaxations

that

of NO

Three

at the nitrergic

theory

problem,

NANC

neurotransmitter

Martin

et al. (146)

the vascular

glycerin

by binding

The first studies began

with

an acidified

factor on the biological

the observations nitrite

cyclase

actions

that

solution,

tions of guanylate substances

of NO essentially

NO gas, generated

activated

crude soluble

(16). Various

such as nitroglycerin,

from

prepara-

cyclic GMP was almost

certainly

the factor

was nitrite

rat anococcygeus

factor

relaxation cyclase

responsible

(159).

that was associated

induced

relaxation

The hypothesis

with activation

of guanylate

in NANC

(85) discov-

and co-workers

vasodilators

of isolated

interact

generation

with

or release

the

relaxing between

at an international

rabbit

for acetylcholineaortic

endothelium factor

the

factor (EDRF)

(64). Based on it was suggested

that EDRF was the same as NO

results were obtained same

the The

discovery NANC

quickly

confirmed

re-

studies

sponsible

analogues

for the synthesis

as NO synthases

(NOS),

fied and cloned

(127).

Most of the credit tory NANC

(158,168).

of NO

The enzymes

from r_-arginine,

have now been characterized,

puri-

that NO is an inhibi-

goes, at least in our opinion,

to Gillespie and co-workers. Gillespie (93,95) identified the inhibitory NANC innervation in the rat anococcygeus muscle and demonstrated that neither VIP nor ATP could be the transmitter

of the NANC

nerves

in this tissue and the

factor

penis

Soon

had

in the

muscle,

involvement

this of NO

thereafter,

inhibition

Gillespie

of the NANC

re-

by AJ”-monomethyl-L-arbiosynthesis,

NANC

clearly

neurotransmitter.

by three other the

mouse

inhibition

relaxations

groups working

anococcygeus

of the

in other

and urogenital

illustrated

nicely

nerve stimulation.

NANC

(92,

systems.

that NO mimicks

ionic

junction

setup,

as the

(204),

vascu-

In addition,

these

the responses

fundus

prejunctional

to

bioassay

the Ca’+-dependent

stimulation

and rat gastric

muscle was such

using a superfusion

setup, we were able to demonstrate

this experimental

biosynthesis

systems,

respiratory

(113)

In Antwerp, nerve

NO

in the anococcygeus

(39,108,139,200),

lease of NO upon

for the discovery

neurotransmitter

known

that

blocked

lar (201)

by L-arginine

or on

upon

138,176).

in-

hibited

tissue

inhibitory

of the NO

on

that

was released

retractor

as inhibitory

Similar

tally synthesized

selectively

blocker

NO

in com-

neurotransmitter

the possible

(96) reported

a specific

gastrointestinal

a pathway

suggested

in the rat anococcygeus

(84,115). Soon thereafter, EDRF was chemically identified as NO (114,167), and it was shown that NO is enzymatifrom L-arginine,

the

neurotransmission.

illustrating

with the observa-

NO

NANC

and bovine

indirectly

ginine,

(85), later termed

EDRF and NO,

meeting

preparations. to trigger

tinding

laxations

that endothelium-dependent

of a relaxing

endothelium-derived many similarities

and Zawadzki

was obligatory

was forwarded

thereafter,

but transient

Because

as putative

by

that EDRF

led to the suggestion

from which

(84,145).

proposed

and potent

(107). In 1980, Furchgott

ered that the endothelium

Soon

acidification

of the

is mediated

factor has several properties

had been used since

be the common

to cause a marked

relaxation

NO (167). Together

mon with EDRF, this information

been

How,

responses

(45). In 1987, it was demonstrated

nitrogen-containing

which

respectively.

to EDRF, the ability

muscle

tion that the inhibitory

also

of EDRF and nitro-

on the NANC

Similar

smooth

different

that hemoglobin

effects

of hemoglobin

to induce

the 19th century in the treatment of angina pectoris, were found to have the same effects, and NO was suggested to NO was shown

relaxant

was not yet recognized.

OXIDE

nerve-mediway (48).

on an apparently

showed

of EDRF and NO,

ever, the meaning NITRIC

the NANC

and effective

years later and working

abolished

(5496).

it reduced

in a selective

in the canine

reileoco-

(36,38,44,54).

With

modulation

of NO

release was clearly demonstrated and further pharmacological characterization of the substance released continned its pharmacological sitnilarity with NO (34,35,74,75). of NO was also reported in the guinea pig intestine,

bovine retractor penis. In their search to identify the NANC neurotransmitter, Gillespie and co-workers isolated an inhibitory factor from the rat anococcygeus and bovine retractor penis that mimicked the action of the inhibitory

urogenital tract and opossum lower using a superfusion bioassay, detection

nerves (98). This inhibitory factor is extracted in an inactive form and is converted to the active form by brief exposure to acid (11,98). It is extremely labile, anionic and

Another method currently often used to indirectly detect NO production involves measurement of the co-product of NO production L-citrulline (52). The following important

or detection 160,210).

of NO

using

esophageal of nitrate

Release human

chemiluminescence

sphincter and nitrite (116,137,

NO as NANC Neurotransmitter

step toward

acceptance

of NO as inhibitory

ter was the purification antisera

toward

in neurons

clearly

pointed

then

nerve

toward

endings

neural

by some

of publications

sulting

of NO as Molecule

in all the NANC

mechanisms implicated

achalasia,

hypertrophic

infantile

sprung’s

disease

and

extensively

NANC

177,183,192), cussions

stenosis,

like

Hirsch-

reviews

literature

only briefly

systems

reports

on some discrepancies

have

on NO

aland

(14,24,

on this issue

and ongoing

dis-

in the literature.

story but that

neurotransmitters

increasingly

clear that NO is not the

co-transmission

mediates

The idea that neurons “Dale’s principle,

of two or even

the inhibitory

release

The co-existence gether

idea

with

the

of producing

that

NANC

neurons

contain

hypothesis

stock (56). Electrophysiological

evidence

was reported

already

ago; two different

mechanisms

of inhibitory

by apamin,

potassium

channels

pig ileum,

apamin

inhibited

the

junction

potential,

whereas

was provided mediated and/or

NO

that

whereas

genes

formed

the

by Burn-

than

10 years

neurotransmisthat blocks

(166). In the guinea

rapid

component

of the

the slower long-lastLater, evidence

the fast component the slower

may be

component

is VIP

(109,214).

Pharmacological studies NAN(: nerve stimulation

dissecting the relaxation to also provide evidence for co-

transmisslon of VIP and NO in, for example, fund,,, and cat guinea pig trachea; relaxation ulation

as

for more than one more

was apamin-resistant.

suggesting

bp ATP,

all the

a bee venom

calcium-dependent

ing hyperpolarization

known

introduced

neurotransmitter

sion were distinguished

more

until the late 1970s. in single neurons to-

all the neurotransmitters

basis for the co-transmitter

inhibitory

can be divided

in a peptidergic

the rat gastric to nerve stem-

component

mediated

by VIP and a nitrergic component (41,72,139,140,204). The respective contribution of NO or VIP in the relaxation varies with the intensity of stimulation with NO being released at low intensity and VIP and NO at high intensity stimulation (41,72,120). ATP and NO has been tine,

I-at pylorus,

species.

NANC the most

rabbit

Evidence for co-transmission of reported in the guinea pig intesportal

vein

and human

region,

in the distal

studies

clearly

chemical

coding

In the gastrointestinal myenteric

or NO

even

in the

whereas

support

the

idea

is the VIP

is

Finally, of

co-

of VIP and NO in neurons tract and ureter

of neurons

tract, chemical

neurons

NO

part (193).

fibers in the gastrointestinal

allows

VIP

rat colon,

in the proximal

with co-localization

and nerve

and

in the

likely candidate

transmission

be empha-

of ATP,

on the tissue studied,

For example,

mediator

it should

contribution

enables

coding

the

of their functions

and

(70,87,184,188). of submucosal

characterization

and projections

and

(70,87).

In-

hibitory NANC neurons contain a mixture of chemical substances like VIP, NO, neuropeptide Y, enkephalin, peptide hi,stidine

isoleucine,

peptide,

ATP,

which

pituitary

may all contribute

The common

and peptide

conclusion,

the

to inhibitory

neurotransmittet

neurotransmission. however,

release

anymore.

seems (87).

In

one neurotmns-

Morphological,

and pharmacological NANC

activating dynorphin,

isoleucine/VIP

neurons

is not acceptable

and

neurons,

histidine

idea that

inhibitory

cyclase

peptide

code for inhibitory

to be NOS

view that

adenylyl

gastrin-releasing

electro-

studies

:a11support

the

release

more than

one

nerves

NO.

under

response.

a single substance,

” dominated thinking of neurotransmitters

capable

same

physiological

By now, it is becoming

In addition,

relative

varies depending

mitter

CO-TRANSMISSION

whole

largely

the

identification

(14,24,88,133,134,155, the

that

even

in this re-

of diseases

in the different

this review

focuses

pyloric

As excellent

neurotransmission

and rather

earlier

sized

morphological

re-

of the Year in Science

in a variety

summarized

(127),

of NO has been reported

impotence

157,175,182,192,205,206). ready

the

on NO as NANC

described

view and has been

until

then,

exponentially

in 1992. By now, the involvement

finding

which

Since

on NO, including increased

of local-

This

of NO,

investigators.

has

42,53,109,121,189,214).

development

(51).

origin

neurotransmitter, in election

neurotransmit-

allowing

and its immunohistochemical

and

was doubted

amount

of NOS,

NOS

ization

929

colon

(31,

CONTROVERSIES ParaZleZYS Serial Hypothesis There

is no doubt

NANC much

that

NO,

neurotransmitters. debate

and unclarity

released

in parallel

different

populations

from the smooth nal muscle

strips,

isolated

an abundant

showing

NO

smooth

from

is

from the same or NO is also released

to VIP, as suggested

Using

amount

release

(106,162-164). receptor linked

either

in response

(106,161).

there

VIP and NO are both

of cells, or whether

muscle

are inhibitory

at present,

whether

from neurons,

the serial hypothesis branes,

VIP and ATP However,

isolated

muscle of data

smooth

in

gastrointesti-

cells or cell memhas

muscle

been cells

reported by VIP

In this model, VIP hinds to a VIP-specific to a membrane-bound pertussis toxin-sensi-

tive

protein.

with

subsequently

This

results activation

synthesis of NO, activation of cGMP and relaxation.

in increased

intracellular

of a membrane-bound of guanylate In addition,

CaLi NOS,

cyclase, production VIP activates VIP-

preferring receptors, triggering a parallel pathway in the smooth muscle cell and resulting in activation of adenylate cyclase,

raise in CAMP and relaxation.

lated myenteric

ganglia

VIP release from iso-

on its turn is blocked

by inhibition

of NO synthesis, implying that VII’ release is dependent on NO production in nerve terminals (105). The authors even hypothesize that the NO produced in the smooth tnuscle cell diffuses back to the nerve tertninals to enhance theory,

the release

nerve

of neural

stimulation

VIP. So, according

induces

NO

production

to this in the

G. E. Boeckxstaens and I’. A. Pelckmans

930

nerve terminal necessary for VIP release and in addition it

is hard to distinguish.

induces release of VIP from the nerve terminals,

serial hypothesis,

which is

Alternatively,

as pointed out in the

VIP may be the main neurotransmitter,

As pointed out above, VIP

its release is dependent on NO synthesis in the nerve termi-

then will relax the smooth muscle by two parallel pathways,

nal and once it is released, VIP stimulates NO production

one via activation

in the smooth muscle, which on its turn diffuses back to

the main pathway for relaxation. of guanylate

and one via activation

cyclase via NO synthesis

of adenylate cyclase (161).

NO would rather function as a neuromodulator

As such,

than a neu-

the nerve

terminal

to further

enhance

VIP release.

Al-

though there is much evidence for the latter theory, there

to smooth

are some unclarities that need further study. Finally, immunohistochemical studies on chemical coding of neurons

muscle relaxation. But, why would the effect of NO produced in the nerve terminals be limited to the nerve termi-

illustrate the complexity of neurotransmission (70,87,184, 196) and have even resulted in new hypotheses proposing

rotransmitter. (161),

In the scheme

proposed

by Murthy

the neural NO has no direct contribution

et al.

nal and not diffuse to the smooth muscle? Although

inter-

neural communication

esting and supported by many data, this serial hypothesis

messenger

certainly does not apply to all NANC

transmitters

canine ileocolonic duce relaxation

junction,

innervations.

relaxation

by the release of combinations

(87).

is mimicked

stimulation-

by NO and com-

NO or a Nitrosothiol? Another

point of discussion concerns

the identity of the

pletely blocked by inhibition of NO synthesis (39,40), excluding a role for VIP. Furthermore, in the canine proxi-

nitrergic neurotransmitter:

mal colon, rat gastric fundus, guinea pig trachea and human

discussion in fact is not confined to NANC

airways, inhibition

of NO syntheses

sion because it also applies to EDRF (82,165).

induced relaxation,

whereas electrically

did not affect VIPinduced responses

It should be emphasized, however, that in contracted be blocked by activation uncontracted relaxation the NANC

of protein kinase C as pointed out Nevertheless,

rat pyloric sphincter

resistant

to NOS

VIP fails to relax the

(189),

inhibitors

and VIP-induced with inhibition

response by NOS inhibitors

in uncontracted

tis-

NO synthesis in smooth muscle may

by Murthy et al. (162).

of

has been reported

tissue (77). Next, it should also be empha-

sized that in the gastrointestinal

tract, interstitial

be responsible

production

for VIP-induced

cells, thought to represent present in the gastrointestinal

that bind NO, like hemoglobin

cells may

of NO. These

the pace maker of the gut, are smooth muscle layer, contain

LY83583,

have a differential

Substances

or hydroxocobalamin,

applied

Nitrovasodi-

on the other hand are simi-

larly affected by these agents. These results have led to the hypothesis that the inhibitory an NO-releasing authentic

molecule

hyperpolarisation

nitrergic neurotransmitter

like a nitrosothiol

NO. Nitrosothiols

relax gastrointestinal

have indeed been shown to

(22,74,90,128).

It should be emphasized,

applied NO is directly injected

in the bathing fluid containing

the inhibitor,

latter has to move to the junction

If the nitrergic

is

rather than

smooth muscle and to mimic NANC

however, that exogenously

ings and smooth

this

effect on exogenously

lators, including nitrosothiols,

neurotransmitter.

NOS in smooth muscle cells. Although

or

pyrogallol or

tion (21,22,90,100,110,119,123,128,174,178).

esis is that so far, immunohistochemical

studies have failed

This

neurotransmis-

NO as compared with relaxations evoked by nerve stimula-

NO synthase and produce NO in response to increased Ca2+ levels (173,212). Another missing link in the serial hypothto demonstrate

is it NO or a nitrosothiol?

reduce the half-life of NO, like hydroquinone,

were clearly blocked (20,38,72,79,122,140). sue, the VIP-induced

of

instead of one or even two neuro-

for example, VIP does not in-

at all (43), whereas electrical

induced NANC

In the

substances

muscle cells

whereas the

between the nerve end-

to block

neurotransmitter

the endogenous

is brought

in contact

with the drugs under study under the same conditions

as

might simply result from methological problems, the immunohistochemical demonstration of NOS in the smooth mus-

NO, it behaves exactly the same as authentic NO. We stud-

cle cell would be an important clarifying piece of evidence in favor of the serial hypothesis. Finally, according to the

ential effect on NO and the NANC

serial hypothesis,

organ bath experiments,

VIP induces an increase in intracellular

Ca2+ activating the smooth muscle NOS. However, in the canine proximal colon, VIP rather induces a decrease in intracellular Ca2+ (122). So, clearly, although there is many data supporting this theory, some unclarities still remain to be solved. In summary, there is no doubt of interplay between NO and VIP, and most likely between other neurotransmitters as well, in mediating NANC inhibition. Whether neurons release both VIP and NO upon stimulation, as one might assume because of their co-localization, populations are activated preferentially

or whether different releasing NO or VIP

ied the effect of several substances, known to have a differneurotransmitter

on the biological

in

activity of the

nitrergic neurotransmitter released from the ileocolonic junction and detected by the bioassay setup described earlier (34,35,74). L-Cysteine, hydroxocobalamin, pyrogallol and hydroquinone all blocked the activity of NO and the nitrergic neurotransmitter to exactly the same extent, whereas they had no effect on nitrosothiols (74). These experiments indicate that different experimental setups might generate completely different results even in the same tissue and suggest that the endogenous neurotransmitter is NO, which is to some extent protected from breakdown. As discussed by Gibson et al. (91), there are several possible mechanisms

NO as NANC

Neurotransmitter

931

NO. Thiols added to the organ bath, for exam-

protecting

ple, have a protective

action against hydroquinone,

fect that is related to the reduced-SH

has also been reported in the rat transverse, descending and

group of the thiol

sigmoid colon and cecum, cat ileum and sheep bladder neck

(49). It is therefore interesting to notice that thiols are shown to be released in the central nervous system upon neural stimulation

and that the concentrations

having such a protective

of thiols

effect are similar to those thought

dismutase,

NO, has recently more, inhibition carbamate tractor

which

the half-life

of

cells in the rat gut (81).

Further-

of superoxide dismutase by diethyldithio-

makes the NANC

penis

prolongs

been shown to be present in myenteric

neurons and interstitial

and the

muscle (27,195). CONCLUSIONS Since its introduction,

to be present in synapses (2 15). Superoxide

tile response, is not confined to these two tissues because it

an ef-

relaxations

ileocolonic

in the bovine re-

junction

sensitive

to

been demonstrated

NANC

tant role in the gastrointestinal,

a very interesting and troubled area of research. The discovery of NO as a physiologically as inhibitory neurotransmitter

of reduction

pathophysiology,

is very limited because of its high diffusion rate (211).

As

respiratory, urogenital and

vascular system. The search for the identity of the neurotransmitter(s) released by these nerves has been and still is

insensitive to this agent before (73,144). Finally, a mathematical model has been described showing that the effect of NO

enormously

to a better

understanding

although

By now, it is becoming

active molecule

increasingly

lease more than one neurotransmitter

with exogenously

applied NO before it

and

clear that NO is not

ited effect on the endogenous they can interact

of physiology

there is still a long way to go.

the whole story but that the inhibitory

whereas

and its role

has undoubtedly contributed

such, substances like superoxide generators will have a limneurotransmitter,

both in

viva and in vitro and are now well accepted to play an impor-

pyrogallol, a superoxide anion generator, whereas they were

in half-life on the sphere of influence

inhibitory mechanisms have

in many different preparations

NANC

nerves re-

that certainly interact

with each other. The exact mode of interaction,

however,

reaches the smooth muscle. Many more studies are needed

is at present a matter of debate. Looking at the increasing

to answer the question whether the nitrergic neurotransmit-

literature on chemical

ter is NO or not. However,

enteric nervous system, there is no doubt that the complex-

one should be careful to con-

clude that it is not NO based on the organ bath experiments mentioned

ity of neurotransmission

coding of neurons, especially in the is much greater than ever thought.

above. References

NO as Contractile Finally,

Agent

to make things even more complicated,

NO not

only relaxes smooth muscle but might be involved in excitation as well. For example, bound contractions tion of electrical

in the opossum esophagus,

(contractions stimulation)

re-

that appear after cessa-

were blocked

of NO synthesis, implying involvement

by inhibition

of NO in this excit-

atory response (2 13). The underlying mechanism is unclear, but overshooting of the membrane potential after rapid cessation of inhibitory contraction.

input may result in depolarization

In the guinea pig small intestine,

on the concentration

used, NO induced a comparable

sponse, namely a moderate nounced

relaxation

rebound contraction

and

depending re-

followed by a pro-

consisting

of a quick and a

sustained component (26). This excitatory response could be blocked by tetrodotoxin and appears to result from activation of cholinergic neurons. Different longitudinal

and to a lesser degree of tachykinergic

mechanisms

seem to be involved in the

muscle of the rat small intestine

and cecum.

Here, NO and nitroderivatives cause a tetrodotoxin-resistant contraction when the tone of the tissue is low that is unaltered by atropine (26,27). Whether this phenomenon is due to a direct effect of NO on the smooth muscle or due to a prejunctional effect independent of action potentials remains to be studied. It is clear, however, that this excitatory effect of NO, either the rebound or the direct contrac-

1. Abrahamsson, H. Vagal relaxation of the stomach induced from the gastric antrum. Acta Physiol. Stand. 89:406-414; 1973. H. Non-adrenergic non-cholinergic nervous 2. Abrahamsson, control of gastrointestinal motility patterns (review). Arch. Int. Pharmacody. Ther. 280:50-61;1986. 3. Abrahamsson, H.; Jansson, G. Elicitation of reflex vagal relaxation of the stomach from pharynx and esophagus in the cat. Acta Physiol. Stand. 77:172-178;1969. 4. Abrahamsson, H.; Jansson, G. Vago-vagal gastro-gastric relaxation in the cat. Acta Physiol. Stand. 88:289-295;1973. 5. Abrahamsson, H.; Jansson, G.; Martinson, J. Vagal relaxation of the stomach induced by apomorphine in the cat. Acta Physiol. Stand. 88:296-302;1973. 6. Allescher, H.D.; Daniel, E.E.; Dent, J.; Fox, J.E.; Kostolanska, F. Extrinsic and intrinsic neural control of pyloric sphincter pressure in the dog. 1. Physiol. 401:17-38;1988. 7. Allescher, H.D.; Tougas, G.; Vergara, P.; Lu, S.; Daniel, E.E. Nitric oxide as a putative nonadrenergic noncholinergic inhibitory transmitter in the canine pylorus in viva Am. J. Physiol. 262:G695-702;1992. transmission by 8. Ambache, H.; Zar, M.A. Non-cholinergic postganglionic motor neurones in the mammalian bladder. J. Physiol. 210:761-783;1970. 9. Ambache, N. Unmasking, after cholinergic paralysis by hotulinium toxin, of a reversed action of nicotine on the mammalian intestine, revealing the prohable presence of local inhibitory ganglion cells in enteric plexuses. Br. J. Pharmacol. Chemother. 6:51-67;1951. 10. Ambache, N.; Edwards, J. Reversal of nicotine action on the intestine by atropine. Br. J. Pharmacol. Chemother. 6:3 ll317;1951.

G. E. Boeckxstaens

932

11. Ambache, N.; Killick, S.W.; Zar, M.A. Extraction from ox retractor penis of an inhibitory substance which mimics its atropine-resistant neurogenic relaxation. Br. J. Pharmacol. 54:409-410;1975. 12. Andersson, K.-E. The pharmacology of lower urinary tract smooth muscles and penile erectile tissues. Pharmacol. Rev. 45:253-308;1993. 13. Andersson, K.-E.; Mattiasson, A.; Sjogren, C. Electrically induced relaxation of the noradrenaline contracted isolated urethra from rabbit and man. J. Urol. 129:210-213; 1983. 14. Andersson, K.E.; Persson, K. Nitric oxide synthase and nitric oxide-mediated effects in lower urinary tract smooth muscles. World J. Urol. I2:274-280;1994. 15. Anuras, S.; Cooke, A.R.; Christensen, J. An inhibitory innervation at the gastroduodenal junction. J. Clin. Invest. 54: 529-535;1974. 16. Arnold, W.P.; Mittal, C.K.; Katsuki, S.; Murad, F. Nitric oxide activates guanylate cyclase and increases guanosine 3’:5’cyclic monophosphate levels in various tissue preparations. Proc. Natl. Acad. Sci. USA 74:3203-3207;1977. 17. Axelsson, K.L.; Ljusegren, M.E.; Ahlner, J.; Grundstrom, N. A novel neurogenic vasodilator mechanism in bovine mesenteric artery. Circ. Res. 65:903-908;1989. 18. Azpiroz, F.; Malagelada, J.-R. Physiological variations in canine gastric tone measured by an electronic barostat. Am. J. Physiol. 247:229-237;1985. 19. Azpiroz, F.; Malagelada, J.R. Vagally mediated gastric relaxation induced by intestinal nutrients in the dog. Am. J. Physiol. 251:G727-735;1986. 20. Bai, T.R.; Bramley, A.M. Effect of an inhibitor of nitric oxide synthase on neural relaxation of human bronchi. Am. J. Physiol. 264:L425-430;1993. 21. Barbier, A.J.; Lefebvre, R.A. Effect of LY 83583 on relaxation induced by non-adrenergic non-cholinergic nerve stimulation and exogenous nitric oxide in the rat gastric fundus. Eur. J. Pharmacol. 219:331-334;1992. 22. Barbier, A.J.M.; Lefebvre, R.A. Influence of S-nitrosothiols and nitrate tolerance in the rat gastric fundus. Br. J. Pharmacol. 111:1280-1286;1994. 23. Barnes, P.J. Neural control of human airways in health and disease. Am. Rev. Respir. Dis. 134:1289-1314;1986. (Review) 24. Barnes, P.J.; Belvisi, M.G. Nitric oxide and lung disease. Thorax 48:1034-1043;1993. 25. Bartho, L.; Lefebre, R.A. Nitric oxide causes contraction in the rat isolated small intestine. Eur. J. Pharmacol. 259:101104;1994. 26. Bartho, L.; Lefebvre, R. Nitric oxide induces acetylcholinemediated contractions in the guinea-pig small intestine. Naunyn-Schmiedeberg’s Arch. Pharmacol. 350:582-584; 1994. 27. Bartho, L.; Lefebvre, R.A. Nitric oxide-mediated contraction in enteric smooth muscle. Arch. Int. Pharmacodyn. 329:53-66;1995. 28. Bayliss, W.M.; Starling, E.H. The movements and innervation of the small intestine. J. Physiol. 24:99-143;1899. 29. Behar, J.; Biancani, P. Effect of cholecystokinin and the octapeptide of cholecystokinin on the feline sphincter of Oddi and gallbladder. Mechanisms of action. J. Clin. Invest. 66: 1231-1239;1980. 30. Behar, J.; Biancani, P. Neural control of the sphincter of Oddi. Gastroenterology 86:134-141;1984. 31. Belai, A.; Burnstock, G. Evidence for coexistence of ATP and nitric oxide in non-adrenergic non-cholinergic

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

46.

and P. A. Pelckmans

(NANC) inhibitory neurones in the rat ileum, colon and anococcygeus muscle. Cell Tissue Res. 278:197-200;1994. Bennett, M.R.; Burnstock, G.; Holman, M.E. Transmission from intramural inhibitory nerves to the smooth muscle of the guinea-pig taenia coli. J. Physiol. 182:541-558;1966. Bjorck, S.; Jansson, R.; Svanvik, J. Influence of electrical vagal stimulation and acetylcholine on the function of the feline gallbladder. Stand. J. Gastroenterol. 18:129-135;1983. Boeckxstaens, G.E.; De Man, J.G.; Dewinter, B.Y.; Herman, A.G.; Pelckmans, P.A. Pharmacological similarity between nitric oxide and the nitrergic neurotransmitter in the canine ileocolonic junction. Eur. J. Pharmacol. 264:85-89;1994. Boeckxstaens, G.E.; De Man, J.G.; De Winter, B.Y.; Moreels, T.G.; Herman, A.G.; Pelckmans, P.A. Bioassay and pharmacological characterization of the nitrergic neurotransmitter. Arch. Int. Pharmacodyn. 329:11-26;1995. Boeckxstaens, G.E.; De Man, J.G.; Pelckmans, P.A.; Cromheeke, K.M.; Herman, A.G.V.; Maercke, Y.M. Ca2 + dependency of the release of nitric oxide from non-adrenergic noncholinergic nerves. Br. J. Pharmacol. 110:1329-1334;1993. Boeckxstaens, G.E.; Mebis, J.; Janssens, J.; Geboes, K.; Herman, A.G.; De Man, J.G.; Pelckmans, P.A. Achalasia: Malfunction of the intrinsic innervation but preserved sensitivity to nitric oxide. Neurogastroenterol. Motil. 6:172;1994. (Abstract) Boeckxstaens, G.E.; Pelckmans, P.A.; Bogers, J.J.; Bult, H.; De Man, J.G.O.L.; Herman, A.G.; Van Maercke, Y.M. Release of nitric oxide upon stimulation of nonadrenergic noncholinergic nerves in the rat gastric fundus. J. Pharmacol. Exp. Ther. 256:441-447;1991. Boeckxstaens, G.E.; Pelckmans, P.A.; Bult, H.; De Man, J.G.; Herman, A.G.; VanMaercke, Y.M. Non-adrenergic non-cholinergic relaxation mediated by nitric oxide in the canine ileocolonic junction. Eur. J. Pharmacol. 190:239246; 1990. Boeckxstaens, G.E.; Pelckmans, P.A.; Bult, H.; De Man, J.G.; Herman, A.G.; Van Maercke, Y.M. Evidence for nitric oxide as mediator of non-adrenergic non-cholinergic relaxations induced by ATP and GABA in the canine gut. Br. J. Pharmacol. 102:434-438;1991. Boeckxstaens, G.E.; Pelckmans, P.A.; De Man, J.G.; Bult, H.; Herman, A.G.; VanMaercke, Y.M. Evidence for a differential release of nitric oxide and vasoactive intestinal polypeptide by nonadrenergic noncholinergic nerves in the rat gastric fundus. Arch. Int. Pharmacodyn. Ther. 318:107-l 15; 1992. Boeckxstaens, G.E.; Pelckmans, P.A.; Herman, A.G.; Van Maercke, Y.M. Involvement of nitric oxide in the inhibitory innervation of the human isolated colon. Gastroenterology 104:690-697;1993. Boeckxstaens, G.E.; Pelckmans, P.A.; Rampart, M.; Verbeuren, T.J.; Herman, A.G.V.; Maercke, Y.M. Nonadrenergic noncholinergic mechanisms in the ileocolonic juncticm. Arch. Int. Pharmacodyn. Ther. 303:270-281;1990. Boeckxstaens, G.E.; Pelckmans, P.A.; Ruytjens, I.F.; Bult, H.; De Man, J.G.; Herman, A.G.; Van Maercke, Y.M. Bioassay of nitric oxide released upon stimulation of nonadrenergic non-cholinergic nerves in the canine ileocolonic junction. Br. J. Pharmacol. 103:1085-1091;1991. Bowman, A.; Drummond, A.H. Cyclic GMP mediates neurogenic relaxation in the bovine retractor penis muscle. Br. J. Pharmacol. 81:665-674;1984. Bowman, A.; Gillespie, J.S. Neurogenic vasodilatation in isolated hovine and canine penile arteries. J. Physiol. 341: 603-616;1983.

NO

47.

48.

49.

50.

5 1.

52.

53.

54.

55. 56. 57. 58. 59.

60.

61.

62.

63.

64.

65.

66.

as NANC

933

Neurotransmitter

Bowman, A.; Gillespie, J.S.; Martin, W. Actions on the cardiovascular system of an inhibitory material extracted from the hovine retractor penis. Br. J. Pharmacol. 72:365-372; 1981. Bowman, A.; Gillespie, J.S.; Pollock, D. Oxyhaemoglobin blocks non-adrenergic non-cholinergic inhibition in the bovine retractor penis muscle. Eur. J. Pharmacol. 85:22 l-224; 1982. Brave, S.R.; Gibson, A.; Tucker, J.F. The inhibitory effects of hydrcquinone on nitric oxide-induced relaxation of the mouhe anc,coccygeus are prevented by native thiols. Br. J. Pharmacol. 109:lOP;1993. (Abstract) BrayJen, J.E. Atropine potentiates neurogenic vasodilatation of rhe feline infraarhital artery: Possible mechanisms. N euruscl. Lett. 78:343-348;1987. Bredt, P.S.; Hwang, P.M.; Snyder, S.H. Localisation of nitric oxide synthase indicating a neural role for nitric oxide. Nature 347:768-770;1990. Bredt, D.S.; Snyder, S.H. Nitric oxide mediates glutamatelinked enhancement of cGMP levels in the cerebellum. Proc. Natl. Acad. Sci. USA 86:9030-9033;1989. Brizzolara, A.L.; Cruwe, R.; Burnstock, G. Evidence for the involvement of hoth ATP and nitric oxide in nonadrenergic, non-cholinergic inhibitory neurotransmission in the r,thblt portal vein. Br. J. Pharmacol. 109:606-608;1993. Ault, H.; Boeckxstaens, G.E.; Pelckmans, P.A.; Jordaens, F.H.; Van Maercke, Y.M. Nitric oxide as an inhibitory nonadrenergic nc>n-cholinergic neurotransmitter. Nature 345: 346-347;1990. Bumhtock, G. Purinergic nerves. Pharmacol. Rev. 24:509581;1972. Burnhtock, G. L)o some nerve cells release more than one neun~transmitter? Neuroscience 1:239-248;1976. Burnhtock, G. Neurotransmitters and trophic factors in the autonomic nervous system. J. Physiol. 3 13:1-35;1981. Burnbtock, G. The non-adrenergic non-cholinergic nervous system. Arch. Int. Pharmacodyn. Ther. 280: 1- 15; 1986. Burn>tock. G.; Campbell, G.; Bennett, M.; Holman, M.E. InhibItIon of the smooth muscle of the taenia coli. Nature 200:581-582;1963. Rum~tock, G.; Campbell, G.; Bennett, M.; Holman, M.E. InnervaticJn of the guinea-pig taenia coli: Are there intrinsic inhibitory nerves which are distinct from sympathetic nerves? Int. J. Neuropharmacol. 3:163-166;1964. Burnrtock, (i.; Camphell. G.; Rand, M.J. The inhibitory innervarion of the taenia of the guinea-pig caecum. J. Physiol. 182:504-526;1966. Burnbtock, G.; Camphell, G.; Satchell, D.; Smythe, A. Evidence that adenosine triphosphate or a related nucleotide is the transmitter buhstance released hy non-adrenergic mhibitory nerves In the gut. Br. J. Pharmacol. 40:668-688;1970. Cannuq, B.J.; Undem, B.J. Evidence that distinct neural pathwalx mediate parasympathetic contractions and relaxations of guinea-prg trachealis. J. Physivl. Lond. 471:25-40; 1993. cherry, P.D.; Furchgott, R.F.; Zawadzki, J.V.; Jothianandan, 1). R<,le of endothelial cells in relaxation of isolated arteries by hradtkmin. Proc. Natl. Acad. Sci. USA 79:2106-2110; 1979. Cicct)cioppo, R.; Onori, L.; Messori, E.; Candura, S.M.; Coccini, T.; Tonini, M. Role of nitric oxide-dependent and -independent mechanisms in peristalsis and accommodation in the rahhit distal colon. J. Pharmacol. Exp. Ther. 270:929937;1994. Clerici, C.; Macquiin-Mavier, I.; Harf, A. Nonadrenergic

67.

68.

69.

bronchodilation in adult and young guinea pigs. J. Appl. Physiol. 67:1764-1769;1989. Cobum, R.F.; Tomita, T. Evidence for nonadrenergic inhihitory nerves in the guinea pig trachealis muscle. Am. J. Physiol. 224:1072-1080;1973. Coleman, R.A.; Levy, G.P. A non-adrenergic inhibitory nervous pathway in guinea-pig trachea. Br. J. I’harmacol. 52: 167-174;1974. Conklin, J.L.; Christensen, J. Local spectalisation at Ileocecal junction of the cat and opossum. Am. J. Phy~iol. 228:

1075-1081;1975. 70. Costa, M.; Brookes, S.J.H.;

71.

72.

73.

74.

75.

76.

77.

78.

79.

80.

81.

82.

83.

Waterman, S.; May<,, R. Enteric neuronal circuitry and transmitters controlling intestinal motor function. In: Holle, G.; Wood, J.P. (eds). Advances in the Innervation of the Gastrointestinal Tract. AmsterJam: Elsevier; 1992: 115. Costa, M.; Furness, J.B. The peristaltic tetlex: An analysis of the nerve pathways and their pharmacology. NnunynSchmiedehergs Arch. Pharmacol. 294:47-60;1976. D’Amato, M.; Curro, D.; Montuschi, P. Evidence for dual components in the non-adrenergic non-cholinergic relaxation in the rat gastric fundus: Role of endogenous nitric oxide and vasoactive intestinal polypetide. J. Auton. Nerv. Syst. 37:175-186;1992. De Man, J.G.; Boeckxstaens, G.E.; I)e Winter, B.Y.; Herman, A.G.; Pelckmans, P.A. Effect of rhiol and supert)xldc dismutase depletion on non adrenergic non cholinergic responses in the rat gastnc fundus. Neurogastroenterc,l. Motil. 7:254;1995. (Ahstracr) L& Man, J.G.; Boeckxstaens, G.E.; De Winter, B.Y.; Moreels, T.G.; Herman, A.G.; Pelckmans, P.A. Comparison of the pharmacological profile of S-nitroaothiola, nitric oxiJe and the nitrergic neurotransmitter in the canine ileocolonic junction. Br. J. Pharmacol. 114:1179-l 184;19?5. De Man, J.G.; Boeckxstaens, G.E.; Herman, A.G.; Pelckmanb, P.A. Effect of potassium channel blockade and alpha 2-adrenoceptor acrivation on the release of nitric oxide from non-adrenerglc non-cholinergic nerves. Br. J. Pharmacol. 112:341-345;1994. De Panti, F.; Azpiroz, F.; Malagelada, J.R. Reflex gastric rtlaxanon in response to distention of the duvdenum.Am. J. Physiol. 252:G595-601;1987. Desai, K.M.; Warner, T.D.; Bishop, A.E.; Palak, J.M.; Vane, J.R. Nitric oxide, and not vasoactive intestinal peptide, as rhe main neurotransmitter of \ragally Induced relaxation of the guinea pig stomach. Rr. J. Pharmacol. 11 3: 1197- 1202; 1994. Doidge, J.M.; Satchell, D.G. Ad rencrglc and nonadrenergic inhihitury nerves in mammalian alrways. J. Auton. Nerv. Syst. 5:83-99;1982. Ellis, J.L.; Undem, B.J. Inhibition by L-N(;-nitro-r.-,~rginine of nunadrenergic-noncholinerglc-mediated relax of human isolared central and peripheral airway. Am. Rev. Respir. Dis. 146:1543-1547;199?. Fahrenkrug. J. VIP as a ncurotransmittcr in the peripheral nerv~1us system. In: Said, S.1. (ed). Vasoactive Intestinal Polypeptide. New York: Raven Press; 1982:X1. Fang, S.; ChrIstensen, J. Manganese superoxide dlsmutase and reduced mcotinamide diaphorase colocalize in the rat gut. Gastroenterology 1@9:1429-1436;1995. Fcehsch, M.; te Poel, M.; Zamora, R.; Deussen, A.; Moncada, S. Understanding the controversy over the Idenrity c>fEDRF. Nature X8:62-65;1994. Funch Jensen, I’. Sphincter of Odd1 morility. Acta Chir. Stand. Suppl. 553:1-35;1990.

G. E. Boeckxstaens

934

84.

85.

86.

87.

88.

89.

Furchgott, R.F. Studies on the relaxation of rabbit aorta by sodium nitrite: The basis for the proposal that the acidactivatable inhibitory factor from the bovine retractor penis is inorganic nitrite and the endothelium-derived relaxing factor is nitric oxide. In: Vanhoutte, P.M. (ed). Mechanisms of Vasodilatation. New York: Raven Press; 1988:31. Furchgott, R.F.; Zawadzki, J.V. The obligatov role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature 288:373-376;1980. Fumess, J.B.; Costa, M. The participation of enteric inhihitory nerves in accommodation of the intestine to distension. Clin. Exp. Pharmacol. Physiol. 4:37-41;1977. Furness, J.B.; Young, H.M.; Pompolo, S.; Bomstein, J.C.; Kunze, W.A.A.; McConalogue, K. Plurichemical transmission and chemical coding of neurons in the digestive tract. Gastroenterology 108:554-563;1995. Garrett, J.R.; Howard, E.R. Myenteric plexus of the hindgut: Developmental abnormalities in humans and experimental studies. Ciba Found. Symp. 83:326-354;1981. Garrett, J.R.; Howard, E.R.; Jones, W. The internal anal sphincter in the cat: A study of nervous mechanisms affecting tone and reflex activity. J. Physiol. 243:153-166;

1974. 90. Gibson, A.; Babbedge, R.; Brave, S.R.; Hart, S.L.; Hobbs, A.J.; Tucker, J.F.; Moore, P.K. An investigation of some Snitrosothiols, and of hydroxy-arginine, on the mouse anococcygeus. Br. J. Pharmacol. 107:715-721;1992. 91. Gibson, A.; Brave, S.R.; McFadzean, I.; Tucker, J.F.; Wayman, C. The nitrergic transmitter of the anococcygeus-NO or not? Arch. Int. Pharmacodyn. 329:39-51;1995. 92. Gibson, A.; Mirzazadeh, S.; Hobbs, A.J.; Moore, P.K. L-NGMonomethyl arginine and L-NG-nitro arginine inhibit nonadrenergic, non-cholinergic relaxation of the mouse anococcygeus muscle. Br. J. Pharmacol. 99:602-606;1990. 93. Gillespie, J.S. The rat anococcygeus muscle and its response to nerve stimulation and some drugs. Br. J. Pharmacol. 45: 404-416;1972. 94. Gillespie, J.S. Non-adrenergic non-cholinergic inhibitory control of gastrointestinal motiiity. In: Wienheck, M. (ed). Motility of the Digestive Tract. New York: Raven Press; 1982:Sl. 95. Gillespie, J.S. Nonpurine, nonpeptide mechanisms. Arch. Int. Pharmacodyn. 303:20-29;1990. 96. Gillespie, J.S.; Liu, X.R.; Martin, W. The effects of Larginine and NG-monomethyl L-arginine on the response of the rat anococcygeus muscle to NANC nerve stimulation. Br. J. Pharmacol. 98:1080-1082;1989. 97. Gillespie, J.S.; Liu, X.; Martin, W. The neurotransmitter of the non-adrenergic non-cholinergic inhibitory nerves to smooth muscle of the genital system. In: Moncada, S. (ed). Nitric Oxide from L-Arginine: A Bioregulatory System. Amsterdam: Elsevier; 1990:147. 98. Gillespie, J.S.; Martin, W. A smooth muscle inhibitory material from the bovine retractor penis and rat anococcygeus muscles. J. Physiol. 309:55-64;1980. 99. Gillespie, J.S.; McGrath, J.C. The spinal origin of the motor and inhibitory innervation of the rat anococcygeus muscles. J. Physiol. 230:659-672;1973. 100. Gillespie, J.S.; Sheng, H. The effects of pyrogallol and hydroquinone on the response to NANC nerve stimulation in the rat anococcygeus and the bovine retractor penis muscles. Br. J. Pharmacol. 99:194-196;1990. 101. Goyal, R.K.; Rattan, S. Nature of the vagal inhibitory innervation to the lower esophageal sphincter. J. Clin. Invest. 55:1119-1126;1975. 102. Goyal, R.K.; Rattan, S. Neurohormonal, hormonal, and drug

103.

104.

105.

106.

107.

108.

109.

110.

111. 112.

113.

114.

115.

116.

117.

118.

119.

and P. A. Pelckmans

receptors for the lower esophageal sphincter. Gastroenterology 74:598-619;1978. Goyal, R.K.; Rattan, S.; Said, S.I. VIP as a possible neurotransmitter of non-cholinergic non-adrenergic inhibitory neutones. Nature 288:378-380;1980. Greeff, K.; Kasperat, H.; Osswald, W. Paradoxe Wirkungen der elektrischen Vagusreizung am isolierten Magen- und Herzvorhofpraparat des Meerschweinchens, sowie deren Beeinflussung durch Ganglienblocker, Sympathicolytica, Reserpin und cocain. Arch. Exp. Path. Pharmak. 243:528545;1962. Grider, J.R.; Jin, J.G. Vasoactive intestinal peptide release and L-citrulline production from isolated ganglia of the myenteric plexus: Evidence for regulation of vasoactive intestinal peptide release by nitric oxide. Neuroscience 54:521526;1993. Grider, J.R.; Murthy, K.S.; Jin, J.G.; Makhlouf, G.M. Stimulation of nitric oxide from muscle cells by VIP: Prejunctional enhancement ofVIP release. Am. J. Physiol. 262:G774-778; 1992. Gruetter, C.A.; Barry, B.K.; McNamara, D.B.; Gruetter, D.Y.; Kadowitz, P.J.; Ignarro, L. Relaxation of bovine coronary artery and activation of coronary arterial guanylate cyclase by nitric oxide, nitroprusside and a carcinogenic nitrosamine. J. Cyclic Nucleotide Res. 5:21 l-224;1979. Hata, F.; Ischii, T.; Kanada, A.; Yamano, N.; Kataoka, T.; Takeuchi, T.; Yagasaki, 0. Essential role of nitric oxide in descending inhibition in the rat proximal colon. Biochem. Biophys. Res. Commun. 172:1400-1406;1990. He, X.D.; Goyal, R.K. Nitric oxide involvement in the peptide VIP-associated inhibitory junction potential in the guinea-pig ileum. J. Physiol. 461:485-499;1993. Ho&s, A.J.; Tucker, J.F.; Gihson, A. Differentiation by hydroquinone of relaxations induced by exogenous and endogenous nitrates in non-vascular smooth muscle: Role of superoxiJe anions. Br. J. Pharmacol. 104:645-650;1991. Hoist, J.J. Peptidergic mechanisms in the pancreas. Arch. Int. Pharmacodyn. 303:252-269;1990. Holst, J.J.; Schaffalitzky de Muckadell, O.B.; Fahrenkrug, J. Nervous control of pancreatic exocrine secretion in pigs. Acta Physiol. Stand. 105:33-51;1979. Ignarro, L.J.; Bush, P.A.; Buga, G.M.; Wood, K.S.; Fukuto, J.M.; Rajfer, J. Nitric oxide and cyclic GMP formation upon electrical field stimulation cause relaxation of corpus cavernosum smooth muscle. Biochem. Biophys. Res. Commun. 170:843-850;1990. Ignarro, L.J.; Byrns, R.E.; Buga, G.M.; Wood, K.S. Endothehum-derived relaxing factor from pulmonary artery and vein possesses pharmacologic and chemical properties identical to those of nitric oxide radical. Circ. Res. 61:866-879;1987. lgnarro, L.J.; Byrns, R.E.; Wood, KS. Biochemical and pharmacological properties of endothelium-derived relaxing factor and its similarity to nitric oxide radical. In: Vanhoutte, P.M. (ed). Mechanisms of Vasodilatation. New York: Raven Press; 1988:427. Iversen, H.H.; Wiklund, N.P.; Gustafsson, L.E. Nitric oxidelike activity in guinea pig colon as determined by effector responses, bioassay and chemiluminescence analysis. Acta I’hysiol. Stand. 152:315-322;1994. Jahnherg, T.; Abrahamsson, H.; Jansson, G.; MartinstIn, J. Gastric relaxatory response to feeding before and after vagotomy. Stand. J. Gastroenterol. 12:225-228;1977. Jahnberg. T.; Martinson, J.; Hulten, L.; Fasth, S. Dynamic gastric response to expansion before and after vagotomy. Stand. J. Gastroenterol. 10:593-598;1975. Jenkinson, K.M.; Reid, J.J.; Rand, M.J. Hydroxocahalamin

NO as NANC

120.

121.

122.

123.

124.

125.

126.

127. 128.

129.

130.

131.

132.

133. 134.

135.

136.

137.

Neurotransmitter

and haemoglobin differentiate between exogenous and neuronal nitric oxide in the rat gastric fundus. Eur. J. Pharmacol. 275:145-152;1995. Jing, L.; lnoue, R.; Tashiro, K.; Takahashi, S.; lto, Y. Role of nitric oxide in non-adrenergic, non-cholinergic relaxation and modulation of excitatory neuroeffector transmission in the cat airway. J. Physiol. 483:225-237;1995. Keef, K.D.; Du, C.; Ward, SM.; McGregor, B.; Sanders, K.M. Enteric inhibitory neural regulation of human colonic circular muscle: Role of nitric oxide. Gastroenterology 105; 1009-1016;1993. Keef, K.D.; Shuttleworth, C.W.R.; Xue, C.; Bayguinov, 0.; Publicover, N.G.; Sanders, K.M. Relationship between nitric oxide and vasoactive intestinal polypeptide in enteric inhibitory neurotransmission. Neuropharmacology 33: 1303 - 13 14; 1994. Kitamura, K.; Lian, Q.; Carl, A.; Kuriyama, H. S-nitrosocystein, but not sodium nitroprusside, produces apaminsensitive hyperpolarization in rat gastric fundus. Br. J. Pharmacol. 109:415-423;1993. Klarskov, P. Non-cholinergic, non-adrenergic inhibitory nerve responses of bladder outlet smooth muscle in vitro. Br. J. Ural. 60:337-342;1987. Klarskov, P.; Gerstenberg, T.C.; Ramirez, D.; Hald, T. Noncholinergic, non-adrenergic nerve mediated relaxation of trigone, bladder neck and urethral smooth muscle in uitro. J. Ural. 129:848-850;1983. Klinge, E.; Sjostrand, N.O. Contraction and relaxation of the retractor penis muscle and the penile artery of the bull. Acta Physiol. Stand. 42O(Suppl.):l-88;1974. Knowles, R.G.; Moncada, S. Nitric oxide synthases in mammals. Biochem. J. 298:249-258;1994. Knudsen, M.A.; Svane, D.; Tottrup, A. Action profiles of nitric oxide, S-nitroso-L-cysteine, SNP, and NANC responses in opossum lower esophageal sphincter. Am. J. Physiol. 262:G840-846;1992. Koster, N.; Madsen, P. The intragastric pressure before and immediately after truncal vagotomy. Stand. J. Gastroenterol. 5:381-383;1970. Lammers, J.W.; Barnes, P.J.; Chung, K.F. Nonadrenergic, noncholinergic airway inhibitory nerves. Eur. Resp. J. 5: 239-246;1992. Lammers, J.W.; Minette, P.; McCusket, M.T.; Chung, K.F.; Barnes, P.J. Nonadrenergic bronchodilator mechanisms in normal human subjects in &lo. J. Appl. Physiol. 64:18171822;1988. Langley, J.N. On inhibitory fibtes in the vagus for the end of the oesophagus and the stomach. J. Physiol. 23:407-414; 1898. Larsson, L.T. Hirschsprungs disease-immunohistochemical findings. Hist. Histopath. 9:615-629;1994. Larsson, L.T.; Shen, 2.; Ekblad, E.; Sundler, F.; Alm, P.; Andersson, K.E. Lack of neuronal nitric oxide synthase in nerve t;hers of aganglionic intestine-a clue to Hirschsprungs disease. J. Pediatr. Gastroenterol. Nutr. 20:49-53;1995. Leckstrom, A.; Ahlner, J.; Grundstrom, N.; and Axelsson, K.L. lnvolvement of nitric oxide and peptides in the inhibitory non-adrenergic, non-cholinergic (NANC) response in bovine mesenteric artery. Pharmacol. Toxicol. 72:194-198; 1993. Lefehvre, R.A. Non-adrenergic non-cholinergic neurotransmission in the proximal stomach. Gen. Pharmacol. 24:257266;19Y3. Leone, A.M.; Wiklund, N.P.; Hokfelt, T.; Brundin, L.; Moncada, S. Release of nitric oxide by nerve stimulation in the human urogenital tract. Neuroreport 5:733-736;1994.

935

138. Li, C.G.; Rand, M.J. Evidence for a role of nitric oxide in the neurotransmittet system mediating relaxation of the rat anococcygeus muscle. Clin. Exp. Pharmacol. Physiol. 16: 933-938;1989. 139. Li, C.G.; Rand, M.J. Nitric oxide and vasoactive intestinal polypeptide mediate non-adrenergic, non-cholinergic inhibitory transmission to smooth muscle of the rat gastric fundus. Eur. J. Pharmacol. 191:303-309;1990. 140. Li, C.G.; Rand, M.J. Evidence that part of the NANC relaxant response of guinea-pig trachea to electrical field stimulation is mediated by nitric oxide. Br. J. Pharmacol. 102:9194;1991. 141. Linden, A.; Skoogh, B.E. NANC responses-role in control of airway tone. Resp. Med. 88:249-265;1994, 142. Liu, SF.; Crawley, D.E.; Rohde, J.A.; Evans, T.W.; Barnes, P.J. Role of nitric oxide and guanosine 3’,5’-cyclic monophosphate in mediating nonadrenergic, noncholinergic relaxation in guinea-pig pulmonary arteries. Br. J. Pharmacol. 107:861-866;1992. 143. Maggi, CA.; Patacchini, R.; Perretti, F.; Tramontana, M.; Manzini, S.; Geppetti, P.; Santicioli, P. Sensory nerves, vascular endothelium and neurogenic relaxation of the guineapig isolated pulmonary artery. Naunyn-Schmiedebergs Arch. Pharmacol. 342:78-84;1990. 144. Martin, W.; Mcallister, K.H.M.; Paisley, K. NANC neurotransmission in the bovine retractor penis muscle is blocked by superoxide anion following inhibition of superoxide dismutase with diethyldithiocarbamate. Neuropharmacol. 33: 1293-1301;1994. 145. Martin, W.; Smith, J.A.; Lewis, M.J.; Henderson, A.H. Evidence that the inhibitory factor extracted from bovine retractot penis is nitrite, whose acid-activated derivate is stabilized nitric oxide. Br. J. Pharmacol. 93:579-586;1988. 146. Martin, W.; Villani, G.M.; Jothianandan, D.; Furchgott, R.F. Selective blockade of endothelium-dependent and glyceryl trinitrate-induced relaxation by hemoglobin and by methylene blue in the rabbit aorta. J. Pharmacol. Exp. Ther. 232: 708-716;1985. 147. Martinson, J. Studies on the efferent vagal control of the stomach. Acta Physiol. Stand. 65:1-24;1965. 148. Martinson, J. Vagal relaxation of the stomach. Experimental re-investigation of the concept of the transmission mechanism. Acta Physiol. Stand. 64:453-462;1965. 149. Martinson, J. The effect of graded vagal stimulation on gastric motility, secretion and hlood flow in the cat. Acta Physiol. Stand. 65:300-309;1965. 150. Martinson, J.; Muten, A. Excitatory and inhibitory effects of vagus stimulation on gastric motility in the cat. Acta Physiol. Stand. 57:309-316;1963. 151. McCrea, E.D.; McSwiney, B.A.; Stopford, J.S.B. The effect on the stomach of stimulation of the peripheral end of the vagus nerve. Q. J. Exp. Physiol. 14:201-233;1925. 152. McSwiney, B.A. Innervation of the stomach. Physiol. Rev. 11:478-514;1931. 153. McSwiney, B.A.; Robson, J.M. The response of smooth muscle to stimulation of the vagus nerve. J. Physiol. 68:124-131; 1929. 154. McSwiney, B.A.; Wadge, W.J. Effects of variations in intensity and frequency on the contraction of the stomach ohmined by stimulation of the vagus nerve. J. Physiol. 65:350356;1928. 155. Mearin, F.; Mourelle, M.; Guarner, F.; Salas, A.; Riverosmoreno, V.; Moncada, S.; Malagelada, J.R. Patients with achalasia lack nitric oxide synthase in the gastro-oesophageal junction. Eur. J. Chn. Invest. 23:724-728;1993. 156. Miura, M.; lnoue, H.; lchinose, M.; Kimura, K.; Katsumata,

G. E. Boeckxstaens

936

157. 158.

159.

160.

161.

162.

163.

164.

165.

166.

167.

168.

169.

170.

171.

172. 173.

174.

U.; Takishima, T. Effect of nonadrenergic noncholinergic inhibitory nerve stimulation on the allergic reaction in cat airways. Am. Rev. Respir. Dis. 141:29-32;1990. Moncada, S.; Higgs, A. The L-arginine-nitric oxide pathway. N. Engl. J. Med. 329:2002-2012;1993. Moncada, S.; Palmer, R.M.; Higgs, E.A. Biosynthesis of nitric oxide from L-arginine. A pathway for the regulation of cell function and communication. Biochem. Pharmacol. 38: 1709-1715;1989. Murad, F.; Mittal, C.K.; Arnold, W.P.; Katsuki, S.; Kimura, H. Guanylate cyclase: Activation by azide, nitro compounds, nitric oxide, and hydroxyl radical and inhibition by hemoglobin and myoglobin. Adv. Cyclic. Nucleotide Res. 9:145158;1978. Murray, J.; Bates, J.N.; Conklin, J.L. Nerve-mediated nitric oxide production by opossum lower esophageal sphincter. Dig. Dis. Sci. 39:1872-1876;1994. Murthy, K.S.; Grider, J.R.; Jin, J.-G.; Makhlouf, G.M. lnterplay of VIP and nitric oxide in the regulation of neuromuscular activity in the gut. Arch. lnt. Pharmacodyn. 329:27-38; 1995. Murthy, KS.; Jin, J.G.; Makhlouf, G.M. Inhibition of nitric oxide synthase activity in dispersed gastric muscle cells by protein kinase C. Am. J. Physiol. 266:G161-G165;1994. Murthy, KS.; Makhlouf, G.M. Vasoactive intestinal cyclase-activating peptidepeptide/pituitary adenylate dependent activation of membrane-bound NO synthase in smooth muscle mediated by pertussis toxin-sensitive Gil-2. J. Biol. Chem. 269:15977-15980;1994. Murthy, K.S.; Zhang, K.M.; Jin, J.G.; Grider, J.R.; Makhlouf, G.M. VIP-mediated G protein-coupled Ca2+ influx activates a constitutive NOS in dispersed gastric muscle cells. Am. J. Physiol. 265:G660-671;1993. Myers, P.R.; Minor, R.L.J.; Guerra, R.J.; Bates, J.N.; Harrison, D.G. Vasorelaxant properties of the endotheliumderived relaxing factor more closely resemble S-nitrosocysteine than nitric oxide. Nature 345:161-163;1990. Niel, J.P.; Bywater, R.A.R.; Taylor, G.S. Apamin-resistant post-stimulus hyperpolarization in the circular muscle of the guinea-pig ileum. J. Auton. Nerv. Syst. 9:565-569;1983. Palmer, R.M.; Ferrige, A.G.; Moncada, S. Nitric oxide release accounts for the biological activity of endotheliumderived relaxing factor. Nature 327:524-526;1987. Palmer, R.M.; Ferrige, A.G.; Moncada, S. Vascular endotheha1 cells synthesize nitric oxide from L-arginine. Nature 333: 664-666;1988. Paton, W.D.M.; Vane, J.R. An analysis of the responses of the isolated stomach to electrical stimulation and to drugs. J. Physiol. 165:10-46;1963. Pearson, G.T.; Davison, J.S.; Collins, R.C. Petersen, O.H. Control of enzyme secretion by non-cholinergic, nonadrenergic nerves in guinea pig pancreas. Nature 290;259261;1981. Pelckmans, P.A.; Boeckxstaens, G.E.; Van Maercke, Y.M.; Herman, A.G.; Verbeuren, T.J. Acetylcholine is an indirect inhibitory transmitter in the canine ileocolonic junction. Eur. J. Pharmacol. 170:235-242;1989. Persson, C.G.A. Inhibitory innervation of cat sphincter of Oddi. Br. J. Pharmacol. 58:479-482;1976. Publicover, N.G.; Hammond, E.M.; Sanders, K.M. Amplification of nitric oxide signalling by interstitial cells. Proc. Natl. Acad. Sci. USA 90:2087-2091;1993. Rajanayagam, M.A.; Li, C.G.; Rand, M.J. Differential effects of hydroxocobalamin on NO-mediated relaxations in rat aorta and anococcygeus muscle. Br. J. Pharmacol. 108:3-5; 1993.

and I’. A. Pelckmans

175. Rajfer, J.; Aronson, W.J.; Bush, P.A.; Dorey, F.J.; lgnarro, L.J. Nitric oxide as a mediator of relaxation of the corpus cavemosum in response to nonadrenergic, noncholinergic neurotransmission. N. Engl. J. Med. 326:90-94;1992. 176. Ramagopal, M.V.; Leighton, H.J. Effects of NG-monomethyl-L-arginine on field stimulation-induced decreases in cytosolic Ca ‘+ levels and relaxation in the rat anococcygeus muscle. Eur. J. Pharmacol. 174:297-299;1989. 177. Rand, M.J. Nitrergic transmission: Nitric oxide as a mediator of non-adrenergic, non-cholinergic neuro-effector transmission. Clin. Exp. Pharmacol. Physiol. 19:147-169;1992. 178. Rand, M.J.; Li, C.G. Differential effects of hydroxocohalamin on relaxations induced by nitrosothiols in rat aorta and anococcygeus muscle. Eur. J. Pharmacol. 241:249-254; 1993. 179. Rayner, V. Characteristics of the internal anal sphincter and the rectum of the vervet monkey. J. Physiol. 286:383-399; 1979. 180. Richardson, J.; Beland, J. Nonadrenergic inhibitory nervous system in human airways. J. Appl. Physiol. 41:764-770; 1976. 181. Saenz de Tejada, I.; Blanco, R.; Goldstein, I.; Azadzoi, K.; de las Morenas, A.; Krane, R.J.; Cohen, R.A. Cholinergic neurotransmission in human corpus cavernosum. 1. Responses of isolated tissue. Am. J. Physiol. 254:H459-H467; 1988. 182. Saenz de Tejada, 1.; Goldstein, I.; Azadzoi, K.; Krane, R.J.; Cohen, R.A. Impaired neurogenic and endotheliummediated relaxation of penile smooth muscle from diabetic men with impotence. N. Engl. J. Med. 320:1025-1030;1989. 183. Sanders, K.M.; Ward, S.M. Nitric oxide as a mediator of nonadrenergic noncholinergic neurotransmission. Am. J. Physiol. 262:G379-392;1992. 184. Schemann, M.; Schaaf, C.; Mader, M. Neurochemical coding of enteric neurons in the guinea pig stomach. J. Comp. Neurol. 353:161-178;1995. 185. Sifrim, D.; Janssens, J.; Vantrappen, G. A wave of inhibition precedes primary peristaltic contractions in the human esophagus. Gastroenterology 103:876-882;1992. 186. Sifrim, D.; Janssens, J.; Vantrappen, G. Failing deglutitive inhibition in primary esophageal motility disorders. Gastroenterology 106:875-882;1994. 187. Skoogh, B.-E.; Lofdahl, C.-G.; Lothwall, J.; Svedmyr, N. Non-adrenergic inhibition nerves to ferret trachea do not go with cholinergic nerves. Am. Rev. Respir. Dis. 133:A116; 1986. (Abstract) 188. Smet, P.J.; Edyvane, K.A.; Jonavicius, J.; Marshall, V.R. Colocalization of nitric oxide synthase with vasoactive intestinal peptide, neuropeptide Y, and tyrosine hydroxylase in nerves supplying the human ureter. J. Ural. 152:1292-1296; 1994. 189. Soediono, P.; Burnstock, G. Contribution of ATP and nitric oxide to NANC inhibitory transmission in rat pyloric sphincter. Br. J. Pharmacol. 113:681-686;1994. 190. Speakman, M.J.; Walmsley, D.; Brading, A.F. An in vitro pharmacological study of the human trigone-a site of nonadrenergic, non-cholinergic neurotransmission. Br. J. Urol. 61:304-309;1988. 191. Stadaas, J.; Aune, S. lntragastric pressure-volume relationship before and after vagotomy. Acta Chir. Stand. 136:61 l615;1970. 192. Stark, M.E.; Szurszewski, J.H. Role of nitric oxide in gastrointestinal and hepatic function and disease. Gastroenterology 103:1928-1949;1992. 193. Suthamnatpong, N.; Hata, F.; Kanada, A.; Takeuchi, T.; Yagasaki, 0. Mediators of nonadrenergic, noncholinergic inhi-

NO

194.

195.

196.

197.

198.

199. 200.

201.

202.

203.

204.

as NANC

Neurotransmitter

bition in the proximal, middle and distal regions of rat colon. Br. J. Pharmacol. 108:348-355;1993. Taylor, S.M.; Pare, P.D.; Schellenberg, R.R. Cholinergic and nonadrenergic mechanisms in human and guinea pig airways. J. Appl. Physiol. 56:958-965;1984. Thornbury, K.D.; Peake, J. Characteristics of the non-adrenergic, non-cholinergic poststimulus contraction of the hladder neck muscle in sheep. J. Physiol. 473:97P;1993. Timmermans, J.-P.; Scheuermann, D.W.; Stach, W.; Adriaensen, D.; De Groodt-Lasseel, M.H.A. Functional morphology of the enteric nervous system with special reference to large animals. Eur. J. Mnrphol. 30:113-122;1992. Toda, N. Non-adrenergic, non-cholinergic innervation in monkey and human cerebral arteries. Br. J. Pharmacol. 72: 281-283;1981. Toda, N. Relaxant responses to transmural stimulation and nicotine of dog and monkey cerebral arteries. Am. J. Physiol. 243:H145-H153;1982. Toda, N. Hemolysate inhibits cerebral artery relaxation. J. Cereb. Blood Flow Metah. 8:46-53;1988. Toda. N.; Baba, H.; Okamura, T. Role of nitric oxide in nonadrenerglc, non-cholinergic nerve-mediated relaxation in dog duodenal longitudinal muscle strips. Jpn. J. Pharmacol. 5.3:281-284;1990. T’oda, N.; Okamura, T. Possible role of nitric oxide in transmittlng information from vasodilator nerve to cerebroarterial muscle. Bioch. Biophys. Res. Commun. 170:308313;199@. Tottrup, A.; Forman, A.; Funch-Jensen, P.; Raundahl, U.; Andersson, K.-E. Effects of postganglionic nerve stimulation in oesophageal achalasia: iin in vitro study. Gut 3 1;17-20; 19Y@. Troncon, L.E.A.; Thompson, D.G.; Ahluwalia, N.K.; Barlo\v, J.; Heggie, L. Relations between upper abdominal symptoms and gastric distension abnormalities in dysmotility like functional dyspepsia and after vagotomy. Gut 37:17-22; 1995. Tucker, J.F.; Brave, S.R.; Charalambous, L.; Hobbs, A.J.; Gthson, A. L-NG-nitro arginine inhibits non-adrenergic, non-cholinergic relaxations of guinea-pig isolated tracheal smoclrh muscle. Br. J. Pharmacol. 100:663-664;1990.

937

205.

206.

207. 208.

209.

210.

211.

212.

213.

214.

215.

Vanderwinden, J.M.; De Laet, M.-H.; Schiffmann, S.N.; Mailleux, P.; Lowenstein, C.J.; Snyder, S.H.; Vanderhaeghen, J.-J. Nitric oxide synthase distribution in the enteric nervous system of Hirschsprung’s disease. Gastroenterology 105:969-973;1993. Vanderwinden, J.M.; Mailleux, P.; Schiffmann, S.N.; Vanderhaeghen, J.-J.; De Laet, M.-H. Nitric oxide synthase activity in infantile hypertrophic pytoric stent)sIs. N. Engl. J. Med. 327:511-515;1992. Veach, H.O. Studies on the innervation of smoc>th muscle. Am. J. Physiol. 71:229-264;1925. Waterman, S.A.; Costa, M.; Tonmi, M. Accommodation mediated hy enteric inhibitory reflexes In the isolated guinea-pig small intestine. J. Physiol. 474:539-546;1994. Wiencke, A.K.; Nilsson, H.; Nielsen, P.J.; Nyhorg, N.C. Nanadrenergic noncholinerglc vasodilation m bovine citiary artery involves CGRP and neurogenic nitric oxide. Invest. Ophthalmol. Vis. Sci. 35:3268-3277;1994. Wiklund, N.P.; Leone, A.M.; Gustafsson, L-E.; Moncada, S. Release of nitric oxide evoked hy nerve stimulation in gulnra-pig intestine. Neuroscience 53:607-611;1993. Wood, J.; Garthwaite, J. Models of the diffusional spread ot nitric oxide-implications for neural nitric oxide sipnalling and its pharmacological properties. Neurc,pharmacot~,gy 33: 1235-1244;1994. Xur, C.; Pollock, J.; Schmidt, H.H.H.W.; Ward, S.M.; Sanders, K.M. Expression of nitric oxide synthase hy interstitial cells of the canine proximal colon. J. Auton. Nerv. Sys. 49: l-14;1994. Yamato, S.; Spechler, S.J.; Goyat, R.K. Role of nitric oxide in esophageal peristalsis in the