[Mechanism of action of alpha-neurotoxins from snake venom on nicotinic cholinoreceptors of sympathetic ganglion neurons in the rabbit].
Effect of alpha-neurotoxins from snake venoms (alpha-bungarotoxin and alpha-cobratoxin, 10(-6)M) on the ACh-induced current and on the fast excitatory postsynaptic current (EPSC) were studied in voltage-clamped neurons of the isolated rabbit superior cervical ganglion treated with atropine (10(-6)M) alpha-Neurotoxins produced potentiating or inhibitory effects on ACh-induced current and only inhibitory effect on EPSC. alpha-Neurotoxins did not change single channel current and lifetime for short-living nicotinic channels and prolonged the lifetime for long-living channels as well as EPSC decay. It is suggested that the inhibitor effect of alpha-neurotoxins on ACh-induced current and on EPSP is due to partial blockade of nicotinic Ach receptors and that their potentiating effect on ACh-induced current results from the prolonged lifetime for long-living channels.
D000818:Animals; D002038:Bungarotoxins / Q000494:pharmacology*; D003039:Cobra Neurotoxin Proteins / Q000494:pharmacology*; D004546:Elapid Venoms / Q000494:pharmacology*; D005728:Ganglia, Sympathetic / Q000187:drug effects*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D011817:Rabbits; D011978:Receptors, Nicotinic / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects
D002038:Bungarotoxins; D003039:Cobra Neurotoxin Proteins; D004546:Elapid Venoms; D007473:Ion Channels; D011978:Receptors, Nicotinic; C025154:alpha-cobratoxin
Mekhanizm deĭstviia alpha-neĭrotoksinov iz zmeinogo iada na nikotinovye kholinoretseptory neĭronov simpaticheskogo gangliia krolika.