beta-Bungarotoxin and parasympathetic nerve blocking action.

I Muramatsu; M Fujiwara; A Miura; K Hayashi; C Y Lee

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PubMed · 7359364

beta-Bungarotoxin and parasympathetic nerve blocking action.

I Muramatsu·M Fujiwara·A Miura·K Hayashi·C Y Lee

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Abstract

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.

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Acetylcholine Animals Bungarotoxins Drug Interactions Electric Stimulation Female Guinea Pigs Heart Rate In Vitro Techniques Male Myocardial Contraction Nicotine Norepinephrine Parasympatholytics Sympathetic Nervous System Vagus Nerve Journal Article

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I Muramatsu, M Fujiwara, A Miura, K Hayashi, C Y Lee. 1980. beta-Bungarotoxin and parasympathetic nerve blocking action.. https://pubmed.ncbi.nlm.nih.gov/7359364/

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