青藤碱对神经肌肉传递的作用

青藤碱对大鼠离体膈神经隔肌标本能可逆性阻滞神经肌肉的传递,呈浓度依赖性抑制作用;对神经干的兴奋性和传导性无明显影响。高Ca~(2+)溶液可拮抗青藤碱对神经肌肉传递的阻滞作用。在小鸡颈二腹肌实验,青藤碱可降低肌肉对ACh的敏感性。青藤碱与琥珀胆碱相似,均使蟾蜍腹直肌标本产生收缩反应。新斯的明不能桔抗青藤碱对神经肌肉传递的阻滞作用,且有加强作用。提示青藤碱具有去极化型肌松药的某些作用特点。

EFFECT OF SINOMENINE (SIN) ON NEUROMUSCULAR TRANSMISSION

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.