EFFECT OF SINOMENINE (SIN) ON NEUROMUSCULAR TRANSMISSION / 中国药理学通报

On the isolated rat phrenic nerve-diaphragm preparation Sin blocked the neuromuscular transmission without affecting the excitability & conductivity of phrenic nerve. Inhibitory effect of Sin on indirect contraction of diaphragm was dose-dependent, increasing with increasing dose & was antagonized by high Ca2+ solution. When the transmission was blocked by Sin, the ACh sensitivity of the chick biventer cervicis muscle was reduced. Like succinylcholine Sin induced the contractile response of the toade rectus abdominis. Neostigmine did not antagonize, but enhanced the blocking effect of neuromuscular transmission of Sin. These results indicate that Sin has some characteristics of depolarizing muscular relaxants.