Abstract
To investigate the pharmacological properties of Ascaris muscle, comparative studies were undertaken on the actions of various drugs on Ascaris muscle, guinea pig isolated ileum and frog isolated rectus preparations. In Ascaris muscle and frog isolated rectus preparations, the contractile activities with acetylcholine (ACh, 10-5 g/ml in Ascaris and 10-6 g/ml in frog rectus) and 1, 1-dimethyl-4-phenylpiperazinium (DMPP, 10-6 g/ml) were inhibited significantly and reversely by d-tubocurarine (d-Tc, 10-5 g/ml) and mecamylamine (Meca, 10-5 g/ml), and slightly by atropine (Atr, 10-4 g/ml) and hexamethonium (C6, 10-4 g/ml), In guinea pig isolated ileum preparation, the contractile activity with ACh (10-6 g/ml) was inhibited markedly and reversely by Atr (10-6 g/ml), while the activity with DMPP (10-6 g/ml) was similarly inhibited by Meca(10-6 g/ml), C6 (10-6 g/ml) and Atr (10-6 g/ml). Although frog isolated rectus preparation was contracted with 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium (McN-A-343, 10-5 g/ml) but not with pilocarpine (10-4 g/ml), Ascaris muscle preparation was not affected by these agonists. Frog isolated rectus preparation was contracted with 5-hydroxytryptamine (5-HT, 10-4 g/ml) but was not affected by histamine (His, 10-3 g/ml) and γ-aminobutyric acid (GABA, 10-4 g/ml), whereas Ascaris muscle was contracted with His (10-3 g/ml) and relaxed with 5-HT (10-4 g/ml) and GABA (10-5 g/ml). These results suggest that Ascaris muscle as well as skeletal muscle have nicotinic receptors and that the Ascaris muscle has properties which differ specifically from skeletal muscle.
