Muramatsu I, Fujiwara M, Miura A, Hayashi K, Lee C Y
J Pharmacol Exp Ther. 1980 Apr;213(1):156-60.
Autonomic effects of beta-bungarotoxin (beta-BuTX), a presynaptic blocking agent at the neuromuscular junction, were examined with parasympathetic (vagus), sympathetic nerve-atrial preparations isolated from guinea pigs. beta-BuTX in concentrations ranging from 0.01 to 10 micrograms/ml abolished the negative inotropic and chronotropic responses to electrical stimulation of the preganglionic trunks of the vagus nerve. This effect was time- and dose-related and was not restored by repeated washings. Such blocking action of beta-BuTX was also obtained when post-ganglionic stimulation was applied. On the other hand, beta-BuTX failed to block the positive inotropic and chronotropic responses to either pre- or postganglionic sympathetic nerve stimulation. The nicotine-induced negative, then positive inotropic and chronotropic effects, under nerve conduction block with tetrodotoxin, were little affected with the application of beta-BuTX. The negative or positive responses to exogenously applied acetylcholine or norepinephrine were also unaffected by beta-BuTX. Thus, beta-BuTX apparently blocks cholinergic transmission in the vagus nerve innervating the guinea-pig heart, probably by acting on the postganglionic nerve terminals, yet does not interfere with preganglionic cholinergic and postganglionic adrenergic transmissions in the sympathetic nerves.
使用从豚鼠分离的副交感神经（迷走神经）、交感神经 - 心房标本，研究了神经肌肉接头处的突触前阻滞剂β - 银环蛇毒素（β - BuTX）的自主神经效应。浓度范围为0.01至10微克/毫升的β - BuTX消除了对迷走神经节前干电刺激的负性肌力和负性变时反应。这种效应与时间和剂量相关，且反复冲洗不能恢复。当施加节后刺激时，也可获得β - BuTX的这种阻断作用。另一方面，β - BuTX未能阻断对节前或节后交感神经刺激的正性肌力和正性变时反应。在河豚毒素导致神经传导阻滞的情况下，尼古丁诱导的先负性、后正性的肌力和变时效应，在应用β - BuTX时几乎没有受到影响。对外源性应用乙酰胆碱或去甲肾上腺素的负性或正性反应也不受β - BuTX影响。因此，β - BuTX显然通过作用于节后神经末梢来阻断支配豚鼠心脏的迷走神经中的胆碱能传递，但不干扰交感神经中的节前胆碱能传递和节后肾上腺素能传递。
