NEW METHODS OF ESTIMATING COUGH DEPRESSING ACTION

Jap. J. Phaymacol. 2, 7-18

NEW METHODS

(1952)

OF ESTIMATING

COUGH DEPRESSING

ACTION

YOSHITOSHI KASE DeEiartment of Pharmacology, Facultyof Medicine,KyushuUniversity, Fukuoka Deparlrxentof Pharmacology, Facultyof Pharmacy,Kumamoto University,Kumamoto Receivedfor publicationMarch6, 1952 So far as I know there are two methods of testing cough depressing drugs. In Ernst's method (1) Lugol's solution is injected into one of the pleural cavity of a cat to cause a state of cough readiness. Another is Eichler-Smiatek's (2), in which cough attacks are brought about in a guinea pig by spraying. sulphuric acid into a compartment in which the animal is kept . These methods, however, are not effectual enough to cause cough attacks constantly at the desired time, and can hardly be employed for evaluation of cough remedies. I therefore have devised two methods. Method 1 is to apply mechanical stimulation to the mucous membranes of the air passages to cause a fit of coughing ; method 2 is to apply electric stimulation to the sensory nerve branch of the trachea. THE PRINCIPLES OF THE METHODS A cough

is a reflex

movement

for

eliminating

foreign

matter

from ,the

air

passages. stimulated

When the mucous membranes of the larynx, trachea, or bronchus are in abnormal ways, the excitation is conducted through the n. vagus to

the cough

center

The impulses and

others,

and

coughing. opened

which from also

Before

In order

to the

explosive

to provoke

go on to the

spinal

nerves

itself.

exact

location

attacks

constant tion.to

acid

to:

velocity.

This

the respiratory

The Ernst's

to portion

of the cough. center is inspired

method

to respiration

one must apply

1) the ends of the the of

and

causes

method

either

sensory

mechani branches

3) is impracticable

at present

since the

is still unknown.

in a constant

makes

n. vagus

larynx, trachea or bronchus ; the n. vagus ; or 3) the cough

method uses a complicated

mucous

(3)iJ. namely

is first shut and then immediately

in animals

stimulation

The application

The Eichler-Smiatek's sulphuric

nerves,

expiration.

of the n. vagus in the mucous membranes of 2) the sensory fibres in the trunk or branches center

cranial

relating

set in, the glottis

cough

or chemical

in the medulla oblongata (Kohts

center

the attacks

by a strong

cal or electric

is located the

causes

apparatus

concentration coughing

by

by means

into a guinea applying

chemical

of which pig

at

a

stimula

membranes

. use of the after

effects

of pleuritis.

Lugol's

solu

8

Y. KASE tion injected five days

into the

later

pleural

cavity

the sensory

nerve

Schaumann

(4) measured

is stimulated

Method 1. Stimulating

by

The Mechanical

the

inflammation.

"cough

readiness

trachea

or

Some

", and

patting

then

the

depressing

effect of Dolantin

Stimulation

of the Mucous Membranes

chest.

by this method.

(Fig. 1)

stimulating

bristles

FIG.

Stimulating

sero-fibrinous

of so-called

pinching

the cough

Apparatus

This comprises

tied around

causes

the cat falls into a state

bristles : 25 or

1.

a sheath.

Stimulating

more

one end of a wire

and

apparatus.

strong

about

curved

30-40

bristles

of a pig

cm. in length.

are

The bristles

radially should be

5 cm long so that they may touch all parts of the inner wall of the trachea. Sheath : Nelaton's catheter (No. 5 or 6) with its round process cut off is used and the stimulating be marked to which

serted

along

the tambour Another

10 cm from

it is exposed

5 kg or more,

trachea

small incision cannula

that

the drugs When

the

and

and

is made the

should

The

at

two

withdrawn

wire points,

into

are

the

exposed.

they have

in the

completely

etherized,

tracheal

and

cannula

is connected

by

at a point

some

inserted

into

is measured V. femoralis

through

and

an

is in

T-tube

to

pressure.

apparatus

at the common

is previously

1 cm below the

trachea

carotid

exposed

by

in order

it.

procedures

while

The

end

in the trachea

method.

may be injected bark

is made.

its free

stimulating

above-mentioned

down after

tube

end.

be marked

are completely

of the intratracheal

Hg-manometer

Most dogs yelp and quiet

the opening

should

is fixed on its back

as far as the mark on the sheath. In the mean time the blood pressure the ordinary

The

when all of the bristles

line of the neck as usually,

for registration

the tracheal

about

are attached

tube.

of Experiment

the middle

into the

into the rubber

when the bristles

at which

dog, weighing

incision

inserted

bristles

it is exposed

the other

The Procedures The

are

with a line at a point the stimulating

one at which tube and

bristles

are state

recovered.

finished,

etherizing

of awakening

from

is stopped. narcosis,

but

ESTIMATION In order

to provoke

OF COUGH cough

attacks

DEPRESSING the

ACTION

stimulating

bristles

9

are

repeatedly

pushed out and pulled in from the sheath, which is held firmly in place by the fingers. Coughing

continues

but ceases

during

No choking undergone

is caused

No fit of coughing itself

is inserted touches

should be

it

cough

cough

curves

frequency

attacks

when

of a constant

of

narcosis,

gentle

the

animal it

dogs.

is

attacks

or barking

of nervous

it difficult

to distinguish

dogs

will

between

but some appear the

large

together two.

expiration with

the

at a time. 2 minutes, time

amplitude

and and

(Fig. 2-4). should be perform

Of course,

cough

dog,

in a dog. to the mucous

in the

important

The cough depressing action of morpntne nydrochloride intravenous). Cough attacks are completely depressed, ed in 105 min. after injection (Dog, 8.4 kg -g-). on any

bifurca it. These

is not

FIG. 8.

the mem

above

each

are registered

tra

to the

seconds of about

As these experiments ed

when

mucous

are the most sensitive The stimulation is given

causes

the

The stimulating

a little

membranes for 20-40 Repeated at intervals

if the stimu

occurs

applied

tion or the trachea

changes

into

the

of the air passages.

bristles

provoke

even

chea.

parts

or any

in respiration

apparatus

branes

FIG. 2." The cough curves in a normal dog. Upper tracing (R.) respiration, lower trac ing (B. D.) blood pressure (mm Hg). Time in 10 sec. intervals. At the arrows the tra cheal mucous membranes stimulated mechani cally (Dog, weight 10.6 kg ').

with its stoppage.

lating sheath

the stimulation

simultaneously

to

state choose

it is possible

(0.8 mg/kg and recover

curves cough

due to whining curves

making

to

10

Y. KASE THE EXAMPLES OF EXPERIMENTS 1.: Activity of Some Opium-alkaloids

(Table

1)

Morphine Hydrochloride On intravenous injection of 0.3 mg/kg, cough attacks came on in just the same manner as before the injection. But when the dose was increased to 0.5 mg/kg,

the

frequency TABLE

and

1.

The

*

the

cough

Minimal

amplitude depressing

effective

of the cough effects

dose

of

some

curves

were

markedly

opium-alkaloids

.

decreased. When 0.8 mg/kg was given the coughing was completely depressed and did not occur again until 105 min. after the injection (Fig. 3). Codeine Phosphate Following intravenous injection of 2 mg/kg cough attacks came on as the result of the stimulation. The amplitude of the cough curves was just the same as before the injection, but the frequency of the attacks slightly decreased. The normal state was restored in 13 minutes. When an increased dose of 3 and 4 mg/kg was injected, the cough attacks were depressed. The complete recovery was seen in 22 resp. 57 minutes (Fig. 4). Di onine It is efficacious only in a dose 5 mg/kg. 2. The Influence of Narcosis On intravenous injection of 10 mg/kg of " Ouropan-Soda " (Evipan-Sodium) cough attacks were completely depressed and the normal state recovered after 22 minutes (Fig. 5).

ESTIMATION

OF COUGH

DEPRESSING

ACTION

FIG. 4.

The cough depressing action of codeine phosphate (4 mg/kg intravenous). Cough attacks recovered in 57 min. after injection. The large and high frequency curves soon after injection represent excited respiration and are different from the cough curves (Dog, 7.4 kg +).

FIG. 5.

The influence of ." Ouropan-Soda (10 mg/kg intravenous) on the cough.. attacks. Recovered to normal at 22 min. after injection (Dog, 9.5 kg ~).

11

Method 2. Electric Stimulation of Ramus Trachealis Nervi Laryngici Cranialis Kandarazki (5,6) stated that cough attacks could tric stimulation-of the ramus trachealis nervi laryngici cranialis enters the larynx after branching off from branches of n. larvng. crap. divide into two branches, The lower one branches off near the lower edge of

be provoked by direct elec cranialis. The n. laryngicus the n. vagus. The sensory the upper and'. the lower. the cricoid cartilage: one

gets to the esophagus and the other joins the n. laryngicus caudalis. At the height of the IV tracheal cartilage the n. laryng. cran. has a branch, ramus trachealis. This branch is comparatively large in a dog. It descends between the trachea and the n. laryng. caud. and joins the n. vagus below. On its way along the trachea many fine branches are distributed -over the upper parts of the trachea. The ramus trachealis is a sensory nerve. The lower parts of the trachea are innerved by other sensory branches that come directly from the n. vagus. The n. laryng. caud. is mainly a motor nerve and it innerves all laryngeal muscles except m. cricothyreoideus. I separated r teach. n. laryng. cyan, and stimulated its central stamp by fre quent constant currents from an argon-tube stimulation generator. The cough attacks can be registered by the same procedures as in method 1. Fig. 6 shows cough curves from electric stimulation. However, the following shortcomings

12

Y. KASE are

unavoidable

in this method.

1. There are variations in the man ner of branching of this nerve. Oi the 25 dogs which I studied, 4 showed normal branchings on both right and left sides, 15 on one side only and 6 no branchings at all. 2. Of the 1.9cases that had branches, cough attacks could be induced in 10 cases only. In 7 cases, although various changes were made in voltage and fre quency of electricity, no cough attacks oc curred although variations were noticed in respiration. Two fully grown dogs, of C~

considerable FIG. 6. The cough curves on a normal dog by electric stimulation on the tracheal nerve branch (Dog, 10.6 kg I-).

account

by phenomena

on the stimulated when

twitches

that

occur

cheal ever,

of

the

is applied the

vocal

to

I used

The

twitches

will cause

occurred tetanus

These

portion are

where

slight

It must mulation.

be noted In

that

was

no

its

on

ramus

the

nerve

of the

the

off.

twitches same tra

stimulation,

so

Increase

in frequency,

how

the opening

and closing

of the

without

the occurrence

show low susceptibility in the

marked

branches

at the height

in my

is

vocal chord

to

tetanus. were

stimulation

of the

as compared

obstruct

in frequent

R. A. 15 cm, and

of

are particularly

low. frequency

only two

the nerves

my experiments,

6 V. and within

and

and considerably

glottis. Of the. 25 experiments, accompanying phenomena.

not be used

trachealis

movements.

voltage

there

ramus

i.e., twitches

the

chords

high

could

smallness

cough,

when the n. laryng. caud. is stimulated

cartilage.

although

than

side' and swallowing

the stimulation

The

other

the

trachealis. 3.

followed

weight, of

stimulation argon-tube

to the by

electric

induction

stimulation

of the sti

currents

generator,

a

peak voltage of 30-50 V. (frequency 2-3/sec.) was required. The use of such high voltage probably stimulates the other nerves and produces the accompany ing phenomena. Although the electric stimulation shortcomings

stimulation

at a fixed strength prevent

it from

method

in inducing being

considered

has cough

the

advantage

attacks,

the

a very, superior

of 'a constant aforementioned method.

Z STl MATION

OF COUCH

DEPRESSING

ACTION

13

SUMMARY 1. Two new methods of estimating cough depressing action have been devis ed, one using mechanical stimulation on the mucous membranes of the trachea and the other using electric stimulation on the ramus trachealis nervi larvngici cranialis, by which cough attacks can be induced easily and registered in cough curves. 2. Method 1 is superior to method 2. It induces cough attacks of constant intensity and frequency without fail. The cough depressing effects can be esti mated quantitatively and the duration of the effects determined precisely. 3. If a dose which gives a depressing effect visible on the cough curves and maintains it for about 20 minutes is taken as the minimal 'effective dose, the ratio in the minimal 'effective dose as determined by method 1 is: Morphine hydrochloride : Codeine phosphate : Dionine=0.5:3.0:5.0 This ratio is in good accordance to that of clinical efficacy., These experiments were carried on under the guidance of Prof. Dr. T. Fukuda and As sociate Prof. B. Nuki at the Pharmacological Department of the Medical Faculty of Kyushu University. I give my sincere and heartfelt thanks to my respected teachers. REFERENCES 1) 2) 3) 4) 5) 6)

ERNST,A. M.: Arch. internat. pharmacodyn . 58, 861 (1938) EICHLER, 0. ANDSMIATEK,A.: Arch. expert Path. u. Pharmakol.194,621 (1940) KOHTS,0.: VirchowsArch. Anatom. u. Physiol.60, 191 (1874) SCHAUMANN, 0.: Arch. exper.Path. u. Pharmakol.196,109 (1940) KANDARAZKI, M.: Arch. f. gesamt. Physiol. 26, 470 (1881) KANDARAZKI, M.: Arch. Anatont.u. Physiol.Anatom. Abt. 1 (1881)