Pharmacological characteristics of cholinoreception in somatic muscles of the nematode, Ascaris suum

Gen. Pharmac.. Vol. II. pp. 141 to 146 ,'C~ Pergamon Press Ltd 1980. Printed in Great Britain

0306-3623 XO 0101-0141502.00'(~

PHARMACOLOGICAL CHARACTERISTICS OF C H O L I N O R E C E P T I O N IN SOMATIC MUSCLES OF THE NEMATODE, ASCARIS S U U M * E. K. ROZHKOVA,T. A. MALYUTINA and B. A. SHISHOV Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the U.S.S.R., Leningrad, and Laboratory of Helminthology, Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R. (Received 26 June 1979) Abstract--l. The ability of some cholinergic drugs to stimulate, potentiate and block contractile re-

sponses of the dorsal muscle strip of Ascaris suum was studied quantitatively. 2. Cholinesterase in nervous and muscle structures of this worm was found histochemically by using acetylthiocholine, butyrylthiocholine and propionylthiocholine as substrates. 3. Anticholinesterase drugs, eserine and phosphacol, potentiated ascarid muscle contractile responses to acetylcholine (ACh), propionylcfioline and butyrylcholine 2-6-fold and did not potentiate contractile responses to suberyldicholine. Relatively high sensitivity of the muscle to ACh was found before its treatment by anticholinesterase drugs. It is suggested that cholinesterase does not take an important part in the interaction between ACh and cholinoreceptors of the muscle. 4. Ascarid muscle sensitivities to the muscarinomimetics, methylfurmethide and F-2268 racemate (2-methyl-4-dimethylaminomethyl-l,3-dioxolan iodide), and to the muscarinolytic, atropine, were found to be 1.7 x 10-4M, 1.6 x 10 -5 M and 7.2 x 10 -2 M, respectively. There was no response to arecoline hydrobromide in concentrations up to 3 × 10 -4 M. The activities of the stereoisomers of F-2268 on the muscle differed by 5-fold. These results suggest that ascarid muscle cholinoreceptors do not possess significant muscarinic sensitivity. 5. Cholinoreception of ascarid muscle resembles nicotinic cholinoreception of leech dorsal muscle. It was found that the cholinoreception of ascarid muscle and that of locomotor muscle and the superior cervical ganglion of some higher vertebrates are different.

INTRODUCTION Body muscles of the parasitic nematode, Ascaris, have a single longitudinal layer of muscle fibres. Each muscle cell is divided into three separate parts: (I) a spindle fibre containing obliquely striated contractile protein, (2) a sacklike belly with a nucleus and (3) an elongated innervation process called an "arm" with "fingers". The arm extends to a nerve cord where neuromuscular junctions are situated (see reviews: de Bell, 1965; Gerschenfeld, 1973; Nasledov & Skorobovichuc, 1974; Toida et al., 1975). Nematode muscle exhibits spontaneous electrical and mechanical activity of myogenic origin (Shishov, 1962; de Bell et al., 1963; del Castillo et al., 1967). This activity is influenced by excitatory and inhibitory nerves (Goodwin & Vaughan Williams, 1963; del Castillo e t al., 1967; Stretton et al., 1978). It was suggested that at neuromuscular junctions of nematodes acetylcholine (ACh) is an excitatory transmitter and 7-aminobutyric acid (GABA) is an inhibitory transmitter (del Castillo et al., 1963; 1964a). The resting potential of ascarid muscle cells is low ( - 3 0 to - 4 0 mV) and does not depend greatly on the concentrations of K ÷ and Na ÷ ions. It is very sensitive to changes in external CI- concentration (del * Dedicated to the memory of Professor M. J. Michelson who made a great contribution to the investigation of the pharmacology of somatic muscle cholinoreception of animals differing in the level of evolutionary development.

Castillo et al., 1964b; Caldwell & Ellory, 1968; Brading & Caldwell, 1971). These properties of nematode muscle make their electrophysiological features differ greatly from those of somatic muscles Of annelids and vertebrates. It has been found that nematode muscles are sensitive to various substances including cholin.ergic drugs (Baldwin & Moyle, 1949; Norton & de Beer, 1957; Krotov, 1961; Natoff, 1969; Michelson, 1973; Rozhkova et al., 1978). The presence of cholinesterase in nervous and muscle tissue (Bueding, 1952; Melechova, 1966; Hutchinson & Probert, 1972) is confirmed by data on the potentiation of nematode muscle response to ACh after treatment with anticholinesterase (anti--ChE) drugs (Norton & de Beer, 1957; Natoff, 1969; Rozhkova et al., 1978). However, most reports mention only qualitative statements about ascarid muscle responses to cholinergic drugs while quantitative estimates of such drug activity are usually absent. Hence, the position of nematode muscles among the objects being studied in comparative pharmacology is not yet clear. The aim of this work was to characterize quantitatively ascarid muscle cholinoreception by using some selectively acting cholinomimetic, cholinolytic and anti-ChE drugs. This data makes it possible to compare some features of cholinoreception of lower worm muscle with adequately estimated cholinoreceptive features of somatic muscles of higher worms (annelids) and with classical nicotinic and muscarinic receptors of higher vertebrates. 141

E. K. ROZHKOVA, T. A. Mat.~t [INA and B. A. SHISHOV

142

ACh 1107M

'

'~

,b

do

,&o 4,0

,doo sdoo,600o

Fig. 1. Value of contraction of ascarid muscle strip vs concentration of acetylcholine (AChl. Numbers refer to molar concentrations of ACh. MATERIALS AND METHODS

In this work Ascaris suum females gathered during pig slaughter were used. The helminths were kept in the laboratory in Ringer solution at 3 8 C for no more than 2 days. Strips of dorsal worm musculature were used for the experiments (Baldwin & Moyle, 19471. To obtain these strips incisions were made in the dorsal part of the body 5 mm from the level of the genitals in the head direction. Then a strip 2 2.5 cm long was excised. As has been shown by Shishov (1962 1963) these strips do not contain neurons that could complicate the estimation of muscle responses to the cholinergic ligands being tested. The strips were placed in a glass bath containing 20 ml ol Ringer solution (NaCI, 150mM: KCI, 3.0mM: CaCl,, 2.7 mM : NaHCO3, 23 mM : pH 7.4) at 38: C. Drugs (0.2 mll were added at various concentrations into the bath. Weak aeration wits used for stirring. Contractions and spontaneous mechanical activity of the muscle were recorded isotonically. The experiment started after the muscle strip was relaxed (Fig. I t to a constant level. Log concentration response curves were obtained for agonists. The cholinomimerit potency wits estimated by using ECs0 (the concentration producing half the maximal response). The maximal response obtained for each agonist was also expressed as a fraction of the maximal response to ACh {the average value for the concentration of ACh producing maximal contractions was 6.4 x l0 ¢ M). This fraction gives some idea of the intrinsic activity {Ariens, 1964~ or efficacy {Stephenson, 19561 and is designated as ":C' (Tables 3 and 4). The cholinolytic activity was characterized by the value A 2 the concentration of the cholinolytic agent in the presence of which the concentration of ACh must be doubled to obtain the initial contraction (Schild, 1957). To study the anti-ChE activities of eserine and phosphacol {paraoxon, E600), their ability to potentiate the effects of agonists hydrolyzed by cholinesterase wits used. The effect of eserine was estimated in the presence of the inhibitor during the whole experimental period with a cholinomimetic agent; the muscle remained in a solution of phosphacol for only 20mm and subsequently the inhibitor was repeatedly washed for I hr before the beginning of the cholinomimetic test. The times of treatment and the concentrations of eserine and phosphacol were chosen on the basis of histochemical experiments with these substances. Histochemical determination of cholinesterase activity was carried out by a direct thiocholine method for freshly frozen tissue sections 201*m thick (Karnovsky & Roots, 1964). Acetylthiocholine, butyrylthiocholine and propionylthiocholine iodides were used as substrates of cholinestera se.

R E S t I.TS A N D D I S C U S S I O N

Cholineslerase and anti-CitE drugs C h o l i n e s t e r a s e activity in the regions o f the nerve trunk a n d n e u r o m u s c u l a r j u c t i o n s as well as in m e m branes and in contractile e l e m e n t s o f muscle cells was found histochemically for f r a g m e n t s of n e m a t o d e body. The histochemical c o l o u r i n g reaction was m o r e

p r o n o u n c e d in n e r v o u s and n e u r o m u s c u l a r regions than in the contractile elements of muscle cells. This reaction took place for all substrales, including acetylthiocholine, b u t y r y l t h i o c h o l i n e and p r o p i o n y l t h i o c h o line. These results are in g o o d agreement with data on e n z y m e localization in the n e m a t o d e b o d y {Lee, 1962: Lui e t a / . , 1963). Anticholinesterase drugs of various kinds, such as c a r b a m a t e s (eserine, neostigmine) a n d a p h o s p h o r organic irreversible inhibitor, p h o s p h a c o l (paraoxonl, were used for the inhibition of the chotineslerase activity of muscle strips. It was found histochemically that the incubation o[ fragments in an eserine solution {I x I0 s M} leads to a c o n s i d e r a b l e decrease m cholinesterase activity after 1 hr. However, intensive c o l o u r i n g in the regions of the nerve trunk and syncytium was still present. T h e reaction with the e n z y m e stops when the eserine c o n c e n t r a t i o n attains 1 x 10 4 M. The same effect is o b s e r v e d in a p h o s p h a c o l solution at the concentration 5 x 10 S M 2 0 m i n after the beginning of inc u b a t i o n of the fragment. Muscle tension and spontaneous activity of ascarid strips are only slightly d e p e n d e n t on c o n c e n t r a t i o n s . But neostigmine [proserine}, unlike eserine and p h o s p h a c o l , leads to a considerable increase in tension and to a considerable c h a n g e in s p o n t a n e o u s activity even at a concentration of 5 x 10 ~ M. F o r this reason we did not use neostigmine in the following tests. As the e x p e r i m e n t s showed, before t r e a t m e n t with a n t i - C h E ascarid muscle exhibits relatively high sensitivity to ACh (Tables I and 2). The sensitivity does not change c o n s i d e r a b l y after the inhibition of c h o b inesterase. P h o s p h a c o l {5 x 10 s MI increases A ( ' h activity six-fold while eserine (1 × 10 "~ MI increases it only three-fold (Table I). The low value of this p o t e n t i a t i n g effect is particularly noticeable if we c o m p a r e it with the s t r o n g a n t i - ( ' h E p o t e n t i a t i o n of ACh action on somatic annelid muscles and tonic l o c o m o t o r muscles of s o m e vertebrates. For example, eserine, proserine and D F P at the same c o n c e n t r a t i o n tl x 10 s MI increase A ( ' h action on leech muscle 15(X)-, 250- and 100-fold, respectively (Flacke & Yeoh, 1968). W h e n applied to b o d y wall muscle of the earthw o r m (David & R o z h k o v a , 1971) and to chick biventer cervicis muscle (Lavrentieva, 1972} proserine (1 × 10 ~ M) increases A C h activity 100-fold. In the a b s e n c e of cholinesterase inhibilors the choli n o m i m e t i c activity of p r o p i o n y l c h o l i n e in ascarid muscle is three times greater than that of ACh. Phosphacol potentiates the p r o p i o n y l c h o l i n e effect only two-fold, and with the inhibition o f muscle cholinesterase the activities of both d r u g s (ACh and propionylcholine} b e c o m e a p p r o x i m a t e l y equal. The p o t e n t i a t i o n by p h o s p h a c o l of the cholinomimetic action was equal for butyrylcholine and ACh (six-fold). P h o s p h a c o l and eserine do not c h a n g e the reaction of ascarid muscle to the b i s q u a l e r n a r y c h o l i n o m i m e tic, suberyldicholine (D-61. The D-6 molecule consists of two ACh molecules, the acid ends of which are b o n d e d by a p o l y m e t h y l e n e chain. The hydrolysis of this molecule t r a n s f o r m s it into a m o n o c h o l i n e ester of suberic acid. At some c o n c e n t r a t i o n s D-6 can serve as a substrate o f acetylcholine- and butyrylcholinesterase (Volkova et ul., 1976). It may he suggested

Nematode somatic muscle cholinoreception

143

Tab!c I. The influence of anti-ChE drugs on ascarid muscle strip sensitivity to hydrolysable cholinomimetics N u m b e r of experiments

Agonists ACh (acetylcholinel ACh + phosphacol 5 x 10 5M A('h + cserine 1 x 10 5M ACh + eserine I x 10 4 M PCh (propionylcholinel P('h + phosphacol 5 x 10 5M PCh + eserine 1 x 10 "~M BCh (butyrylcholinel BCh + phosphacol 5 x 10 ~ M D-6 (suberyldicholinel D-6 + phosphacol 5 x I0 5M D-6 + cscrine I x 10 5 M

II 5 4 4 4 4 3 4 4 5 9

E('~o (M) _+ SEM 6.1 + 1.2 9.5_+2.3 2.9+0.7 2.1 _+ 0.3 2.1 _4-0.3 1.2+0.3 1.6-+0.3 2.9 -+ 1.4 4.7_+0.3 1.4_+0.3 9.0 _+ 2.t

4

x x x x x x x x × x x

10 10 10 10 10 10 10 10 10 10 10

1.3_+0.2 x I0

that the a b s e n c e o f the p o t e n t i a t i o n of D-6 effects is d u e to e q u a l sensitivity of a s c a r i d m u s c l e c h o l i n o r e c e p t o r s to the w h o l e b i s q u a t e r n a r y m o l e c u l e a n d to t h e m o n o q u a t e r n a r y p r o d u c t o f its hydrolysis. Hencel the relatively h i g h A C h - s e n s i t i v i t y of a s c a r i d m u s c l e strips before t h e a p p l i c a t i o n of a n t i - C h E d r u g s a l o n g with the w e a k p o t e n t i a t i n g effect o f p h o s p h a c o l a n d e s e r i n e indicate t h a t t h e significance o f c h o l i n e s t e r a s e in the i n t e r a c t i o n b e t w e e n A C h a n d c h o l i n o r e c e p t o r s of this m u s c l e is n o t very great. O u r e x p e r i m e n t s d o n o t p e r m i t a detailed c h a r a c terization of a s c a r i d m u s c l e c h o l i n e s t e r a s e . H o w e v e r , it c a n be s u g g e s t e d that this c h o l i n e s t e r a s e differs c o n siderably from mammalian acetylcholinesterase and butyrylcholinesterase.

Cholinomimetic and cholinolytic druqs T a b l e s 3 a n d 5 s h o w t h a t the d o r s a l m u s c l e strip of the a s c a r i d e x h i b i t s low sensitivity to m u s c a r i n i c drugs. T h e E C s o value for the m u s c a r i n o m i m e t i c , m e t h y l f u r m e t h i d e , on this m u s c l e was 1.7 × 10 4 M. T h i s v a l u e is 5000 t i m e s lower t h a n t h a t for m e t h y l -

Coefficient of potentiation

~' v ~ " ~' ~' ~' 5 ~' s ~'

6 2 3 2 I 6 I

~

1

f u r m e t h i d e off g u i n e a pig i l e u m ( M i c h e l s o n & Shelk o v n i k o v , 1976). A r a c e m i c p r e p a r a t i o n of F-2268 12-methyl-4-dimethylaminomethyl1,3-diox olan iodide) a n d o n e of its optical i s o m e r s h a v e been f o u n d to be a m o n g the m o s t p o w e r f u l m u s c a r i n o m i m e t i c s (Barlow, 1964). T h e f o r m e r is t h e m o s t active d r u g for g u i n e a pig i l e u m ( E C s o = 1 × 10 S M) a n d o n e of its two s t e r e o i s o m e r s is 100-fold m o r e effective t h a n the o t h e r b e c a u s e m u s c a r i n i c c h o l i n o r e c e p t o r s of h i g h e r v e r t e b r a t e s d i s p l a y a p r o n o u n c e d stereoselectivity (Ger et al., 1976). T h e activity o f the F-2268 r a c e m a t e on the a s c a r i d m u s c l e is 1000 t i m e s lower t h a n t h a t on t h e g u i n e a pig ileum. T h e activities of its stereoi s o m e r s on a s c a r i d m u s c l e are only five t i m e s different (Table 3). T h e effectiveness of the r a c e m a t e corres p o n d s to its n i c o t i n o m i m e t i c activity. M e t h y l f u r methide and arecoline hydrobromide do not have m a r k e d n i c o t i n o m i m e t i c properties. A r e c o l i n e h y d r o b r o m i d e in c o n c e n t r a t i o n s up to 3 × 1 0 - a M did n o t e v o k e a c o n t r a c t i l e r e s p o n s e in ascarid muscle. T h e s e results a n d the low sensitivity of n e m a t o d e

Table 2. The ACh potency on the somatic muscles of ascarid, leech, earthworm and chick before and after inhibition of muscle cholinesterase

ECho of ACh before ChE inhibition E C ~ of ACh after ChE inhibition

m. dorsalis of ascarid

Longitudinal body wall muscle of earthworm

m. dorsalis of leech

m. biventer cervicis of chick

6 x 10-~'M

I x 10 4 M

3 x 10-'~M

1 x 10 4 M

l x 10 ~'M

I × 10 ~'M

4 × 10 7M

t x 10 ~M

Table 3. The action of muscarinomimetics on ascarid somatic muscle

Agonists ACh + p h o s p h a c o l 5 × 10 5 M Arecoline hydrobromide Methylfurmethide F-2268 [racemate) F-2268 (L) F-2268 (D)

N u m b e r of experiments 5 2 7 4 I 2

~ I 0.8 I 1 (/.9

EC5o (M) _+ SEM 9.5 _+ 2.3 × 10 " Ineffective up to 3 × 10 4 1.7 + 0 . 4 × 10 "~ 1.6._+ 0.2 × 10 5 4.0 x 10 ~ 2.5 _+ 0 x 10 5

144

E, K. ROZHKOVA,T. A. MALYUT1NAand B. A, SHISHOV

Table 4. The action of nicotinomimetics on ascarid somatic muscle Agonists

Number of experiments

~

5 4 4 5 4 4 7 4 4 4 4 9 4

I 1 1 1 1 1 0.8 1 0,7 0.8 1 0.9 1

ACh + phosphacol5 x 10 5M PCh + phosphacol5 x 10 5M BCh + phosphacol5 x 10 SM Carbacholine TMA Pentyltrimethylammonium Nictoine DMPP Decamethonium Succinyldicholine Adipyldicholine D-6 + phosphacol 5 x 10 -5 M Sebacoyldicholine

muscle to atropine (see Table 5) suggest that ascarid muscle cholinoreceptors do not possess significant muscarinic sensitivity. This conclusion is in agreement with the data of other investigators (Baldwin & Moyle, 1949; N o r t o n & de Beer, 1957; Natoff, 1969). Some bisquaternary nicotinomimetics such as decamethonium and succinyldicholine have the same low activity as muscarinic agonists on ascarid muscle. These drugs were found to be less active than TMA (see Table 4 and Fig. 2C). Here, it appears that the second cationic head reduces the activity of agonists on ascarid muscle.

pC EC~ 8" 76"

-4-

A

. . . . . . . . . . . . .

9.5 1.2 4.7 4.1 3.1 1.1 3.5 7.0 1.3 1.5 3.4 9.0 4.7

± 2.3 ±0.3 ±0.3 ± 0.5 ± 0.7 _+ 0.2 _+ 0.6 _+ 1.2 ± 0.4 ± 0.3 ± 1.0 ± 2.1 ± 1.0

x 10 7 x 10 (~ x 10 6

x 10 ~' x 10 ~ x 10 5 x 10 x 10 ~ x 10 4 x 10 4 x l0 5 x 10 ~' x 10 ~

The effectiveness of the other bisquaternary cholinomimetics, such as adipyldicholine, D-6 and sebacoyldicholine, is approx one order of magnitude lower than that of ACh. Their activity is approximately the same as that of TMA and pentyltrimethylammonium. Presumably, the presence of a second cationic head in these bisquaternary substances does not affect their effectiveness. This suggestion agrees with the fact that both phosphacol and eserine did not potentiate D-6 effects in ascarid muscle (see previous section). Apparently, the absence of potentiation is due to equal sensitivity of ascarid muscle cholinoreceptors to the PC ECso

CHICK m bivenfer cervicis

ECs0 (M) ± SEM

B

8

EARTHWORM Iongitudincl body woll muscle

-ACh

ACh

5" 4

3 2" I ACh

sPc

0eC SuC Adi

ECso

SuB SIB TMA

C

PCh BCh CCh

Nic

Seb

HIRUDO M E D I C I N A L I S m.dor$olJs

7-ACh

5"

4-

4,

3-

3'

2-

2.

I-

I 041¢ SCK Adip Sub $1b TMA PTMILPCtl BCh CCh Dt/PP Ni¢

ACh

6"

5~

ACh

Suc

8J C ECho

A S C A R I S SUUM m.dorsalis

76-

ACh

ACh

DOC $U¢ AdIp SUB SeB

TMA

PCh BCh CCh

Fig. 2. Values of ECso for some nicotinic agonists in somatic muscles: A--m. biventer cervicis of chick; B longitudinal body wall muscle of earthworm; ~ m . dorsalis of ascarid; D m. dorsalis of leech. The ordinate denotes negative logarithms of molar concentrations: the height of the perpendiculars corresponds to values of ECso: acetylcholine, ACh; decamethonium, Dec; succinyldicholine, Suc: adipyldicholine, Adip; suberyldicholine, Sub; sebacoyldicholine, Seb; TMA; pentyltrimethylammonium, PTMA; propionylcholine, PCh; butyrylcholine BCh; carbacholine, CCh; dimethylphenylpiperazinium, DMPP: nicotine, Nic. Broken line corresponds to the value of ECso for ACh.

Ntc

Nematode somatic muscle cholinoreception

145

Table 5. The action of some cholinergic blocking drugs on ascarid somatic muscle Antagonists

Number of experiments

A2 (M) + SEM

8 5 3

4.4 + 1.1 x l0 -~ 3.8 + 0.8 × 10 s 5.7 +_ 1.7 x 10 6

4 8

1.5 + 0.2 x 10 ~' 7.2 _+ 2.7 x 10 s

Tubocurarine Hexamethonium Tetraethylammonium Mesphenal (3-diphenylacetoxy-met hyl-diethylpropylammoniuml metylsulphonate Atropine

whole D-6 molecule and to the product of its hydrolysis, the monocholine ester of suberic acid. These features distinguish cholinoreception of ascarid muscle from that of locomotor muscles of higher vertebrates, which display very high sensitivity to the bisquaternary cholinomimetics investigated and low sensitivity to T M A (compare Fig. 2, A and C). Unfortunately, quantitative data characterizing cholinoreception of the e a r t h w o r m muscle is very scanty. But the sensitivity of the somatic muscle of the e a r t h w o r m to succinyldicholine a n d sebacoyldicholine differs considerably from that of ascarid muscle (Fig. 2B}. A m o n g the species considered in this work, nicotinic cholinoreception of the leech muscle resembled most that of ascarid muscle (compare Fig. 2, C and D}. Nevertheless, unlike ascarid muscle, leech muscle exhibits lower T M A sensitivity and higher sensitivity to the bisquaternary drugs studied (see Rozhkova, 19731. It has been suggested (Natoff, 1969) that the features of cholinoreceptors of ascarid somatic musculature and of the superior cervical ganglion of the cat are similar. This view is based mostly on the high sensitivity of ascarid muscle to l,l-dimethyl-phenyl-

piperazinium (DMPP), which is known to be a selective and highly active ganglionic cholinomimetic. However, our data indicates that there are many s e l e c t i v e and highly active ganglionic cholinomimetic and cholinolytic drugs that have low activity on ascarid muscle (Tables 4 and 51. Thus, nicotine was 33 times weaker in ascarid muscle than ACh (Table 6) whereas in cat superior cervical ganglion the activities of these two substances are equal (Lukomskaya, 1969). Moreover D-6, which is 6 times stronger than ACh in its ganglionic cholinomimetic effect, is 10 times weaker than ACh on ascarid muscle. The activities of other cholinomimetics and cholinolytics expressed in relative units (Table 6) also differ for these two objects. The activity of hexamethonium, which is a very selective and active ganglionic cholinolytic, was much lower than that of tubocurarine on ascarid muscle. All these results contradict the suggestion of the similarity of cholinoreception in ascarid muscle and cat superior cervical ganglion. It is possible that the high effectiveness of D M P P was due to its structural similarity to piperazine, which is an agonist at GABA receptors. D M P P includes a phenyl ring and two methyl groups which distinguish it from piperazine. Hence, it is possible that D M P P affects G A B A receptors as an antagonis-

Table 6. The potency of some cholinergic drugs on ascarid somatic muscle as compared to that on the cat superior cervical ganglion* Drugs

m. dorsalis of ascarid Cholinomimetics--relative potency ACh potency was taken to be equal to 1 ECso ofACh = 9.5 × 10-VM

ACh + anti-ChE DMPP TMA Nicotine Pentyltrimethylammonium D-6 + anti-ChE

Hex Tubocurarine Mesphenal TEA

1 1 1:33 1:33 1:10 I : 10

Superior cervical ganglion of cat

EC5o ofACh = 0.014,uM (intra-arterial injection) 1 1 1: 13 1 1:3 6

Cholinolytics--relative potency Hexametbonium (Hex) potency was taken to be equal to 1 A, ofHex = 3.8 x 10-SM A 2 ofHex = 0.033 I~M 1 1 86 5 3 1/20 10 1/20

* The data for the cat superior cervical ganglion is taken from Lukomskaja (1969).

146

E, K. ROZHKOVA, T. A. MALYUTINA and B. A. SHISHOV

tic agent rather than as an agonist. In this case the D M P P activity in ascarid muscle may depend on the drugs's ability to act simultaneously as both an ACh agonist and a G A B A antagonist. This suggestion needs further investigation. REFERENCES ARIENS E. J. (ed.)(1964) Molecular Pharmacology, VoL I. Academic Press, New York. BALDWIN E. & MOYLE V. 11947) An isolated nerve-muscle preparation from Aseuris lumhrieoides. J. exp. Biol. 23. 277 291. BALDWIN E. & MOYLt~ V. 11949) A contribution to the physiology and pharmacology of Asearis lumhrieoides from the pig. Br. J. Pharmac. 4, t45 152. BARLOW R. B. (1964) Introduction to Chemical Pharmacology, 2nd edn. Methuen, London. BELL J. T. DE (1965) A long look at neuromuscular junction in nematodes. Q. Ree. BioL 40, 233 251. BELL J. T. old, CASTILLO J. DEL & SAN('ER V. (19631 Electrophysiology of the somatic muscle cells of .4searis lumhrico[des. J. Cell. Comp. PhysioL 62, 159 177. BRADING A. F. & CALDWELL P. C. ~1971 ) The resting membrane potential of the somatic musclc cells of Ascaris lumbrieoides. J. Physiol., Lond. 217, 605-624. BUI!DING E. 11952) Acetylcholinesterase activity of Schistosoma mansoni. Br. J. Pharmae. 7, 563 566. CALDWELL P. C. & ELLORY J. C. (19681 Ion movements in the somatic muscle cells of Asearis lumhicoides. J. PhysioL, Lond. 197, 75 76. CASTILLO J. nt~L, MELLOW. C. Dr! & MORALt~S T, (19631 The physiological role of acetylcholine in the neuromuscular system of Ascaris lumhricoides. Arehs Int. Physiol. Biochem. 71, 741 757. CASTILLO J. DEL, MELLOW. C. DE & MORALES T. (1964a) Inhibitory action of ;-aminobutyric acid (GABA) on Ascaris muscle. Experientia 20, 141 145, CASTILLO J. DI~L, MELLOW. C. DE & MOP,ALES T. (1964b) Influence of some ions in the membrane potential of Asearis muscle. J. ,qen. Physiol. 48, 129-140. CASTILLO J. DEE, MELLOW. C. I)1 & MORALES T. (19671 The initiation of action potentials in the somatic musculature of Ascaris lumhricoides. J. exp. Biol. 46, 263 279. DAWD O. F. & ROZHKOVA E K. 11971) Cholinoreception of locomotor muscles of the earthworms. J. Erol. Biochem. Physiol. 7, 59 65. In Russian. FLACKE W. & YEOn T, S. t1968) The action of some cholinergic agonists and anticholinesterase agents on the dorsal muscle of the leech. Br. 3, Pharrm,'. 33, 145 153. GER B, A., ZEIMAI, E. V., MI('HEL~)N M. YA., SOKOLOV G. P., PROTAS L. L. & Sm!LKOVNIKOVS. A. (1976) Comparative data on sterioseIectivity of cholinoreceptors. J. Evol. Biochem. Physiol 12, 473 475. In Russian. GeRSHI/NI:ELD H. M. (19731 Chemical transmission in invertebrate central nervous systems and neuromuscular junctions. Physiol. Rev. 51, 1 119. GOODWIN L. G. & VAUGItAN WILLIAMS E. M. 11963) Inhibition and neuromuscular paralysis in Ascaris lumhrico[des. J. Physiol., Lond. 168, 857 871. HL'Tf'ItlNSON G. W. & PROBERT A. G. 11972) Asearis slomT:

kinetic properties, tissue specificity and uhrastructural location ofcholinesterases. Exp. Parasit. 32, 109 116. KARNOVSKY M. S. & ROOTS L (19641 A "'direct-coloring'" thiocholine method for cholinesterases. J. Histochem Cvtochem. 12, 219 226. KRt)IOV A. I. (1961) E.':perimental Therapeutics O/ItehnmtIw.SeL~ lEd[ted by MIiD(;IZ M.) In Rnssian. LAVRI¢NTIEVA V. V. 11972) Cholinoreceptive properties of somatic muscles Protostomia and Deuterostomia. Thesis. IEM, Leningrad. In Russian. L~L! D. L. 11962) The distribution of cstcrase enzymes m Asearis hmlhrieoides. Parasitology 52. 241 260. LtI A., BI!CtiJAC S., KRVAVI('A S. & CORI(" D. (19631 On the activity and localization of cholinesterase in Ascaris suumGoetz, l'et. Arh.. Za~treh. XXXIII, II 12, 307 311. LUKOMSKAYA N. YA. (1969} Change in cholinergic sensitivity after denervation of the superior cervical ganglion in the cat..]. Et,ol. Biochem. Physiol. 5, 65 73. In Russian. MELtCHOVA A. G. 11966) Cholinesterase activity of Asearis suum. Proe. Sci. Con]i VOG+ 2. In Russian, MJcmt,so~ M. J. (1973~ Pharmacolog~ of cholinergic ~,}stern in some other phyla (Nematodes), In Comparatire Pharmacology (International Encyclopedia of Pharmacology Theraputics, Section 85) Vol. I, pp, 200 204. Pergamon Press. OxR~rd. MI('tIEI,SON M. J. & SII[51,KOVNIKOX.,S. A. (1976l Isotonic and isometric responses of diffeent tonic muscles to agonists and antagonists. Br. J. Pharnlae. 56, 457 467. NASI.tDOV G. A. & SKOROBOVWHt~K N. F. {1974) Neuromuscular system of worm. In The Derelopment of Contraetile Function in Lounmm)r Muscles, pp. 138 144. Nauka, Leningrad. In Russian. NAJOVF J. L. [1969)The pharmacolog,, of cholinoreceptor in muscle of Ascuri,~ honhricoides rar suum. Br. J. Pharmac. 37, 251 257. NORION S. & BIER E. G. 1)1 (1957) Investigations on the action of piperazine on ,4scaris lumhrieoides. ,4m..1. Trop. Med. Hyg. 6, 898 905. ROZHKOVA E. K+ 11973) Pharmacology of cholinergic systems in annelids. In Comparative Pluu'macology (International Encyclopedia of Pharmacology and Therapeutics Section 85) Vol. 1. pp 169 189. ROZtIKOVA E. K., MALYUT[NA T. A., Sl-tlSltOV B. A. [1978) The effect of cholinomimetic and anticholinesterase drugs upon the somatic muscles of the ringworm Asearis suum. J. Erol. Biochem. Physiol. 14. 597 599. In Russian. SeinED H. O. (1957t Drugs antagonism and pA,. Pharmae. Rer. 9, 242 246. SmSHOV B. A. 11962 19631 O n the nature ofascaride contractile activity Hebnintholo,qia 4, 446 455. In Russian. Srt pm!xsoN R. P. (19561A modification of receptor theory. Br. J. Phurnlae. II, 379 393. STRI'ITON A. 0 . W., FISHP(X)L R. M., S()U fI+|GAT[! E., DONMO'~I R I. E., WAIiRONI) I. P., Mosfis I. E. R. & KASS I. S. 11978) Structure and physiological activity of the m o t o n e u r o n s of the nematode Aseuris. Proe. Natn. Acad. Sci. U.S.A. 75, 3493 3497. TOIDA N., KURP,'AMA H., TASHIRO N. & 110 Y. 11975) Obliquely striated muscle. Physiol. Rer. fir. 71X) 756. VOLKOVA R. |., KIREt VA E. G., MI('HliLSON M. J. & Mt!SKI'

G. A. 11976} The enzymatic hydrolysis and reversible binding of suberyldicholine by cholinesterases. H~prosv reed. khim. 22, 64 71. In Russian.