Abstract
Pharmacological properties were studied on IS-toxin (Gohgi et al. 1973 and Hirayama et al. 1970) and Surugatoxin (Kosuge et al. 1972 and Gohgi et al. 1973: S-toxin) isolated from the Japanese ivory shell, Babylonia japonica. The suppression of spontaneous motility. mydriasis and relaxation of the nictitating membrane were induced by these toxins (i.p.) in cats. The effects of S-toxin on the inner plexus of rat and guinea pig small intestine were investigated in vitro. S-toxin reduced or eliminated the contractile responses of this intestine to DMPP or nicotine, but the toxin did not affect the contraction due to McN-A-343. When S-toxin was applied to cat superior cervical ganglion, it reduced or abolished the contractile response of the nictitating membrane induced by DMPP, while the contraction due to McN-A-343 was hardly affected by this toxin. Furthermore. the toxin (applied to the ganglion) inhibited the postganglionic potentials due to stimulation of the preganglionic fiber. These data indicate that S-toxin acts as a specific inhibitor on the nicotinic receptors of the autonomic ganglia. The ganglioplegic action of S-toxin was less potent (about 1 30) than IS-toxin.
