Resistance of the snake neuromuscular junction to the blocking effect of beta-bungarotoxin.
beta-Bungarotoxin at a concentration of 0.05 microM was enough to block successively the nerve-evoked intracellular action potential of muscle fiber, the end-plate potential, and miniature end-plate potentials within 60, 90, and about 180 min, respectively, in the isolated nerve-muscle preparation of the frog. On the other hand, at the snake neuromuscular junction beta-bungarotoxin caused an initial transient reduction and a following sustained facilitation of the miniature end-plate potential discharge, but did not block the nerve-evoked intracellular action potential of muscle fiber at a concentration of as high as 50 microM over 4 h. The results show that beta-bungarotoxin binds to snake motor nerve ending without leading to the transmission block, probably due to lacking the target of action.
Xu
K
K
Laboratory of Molecular Neuropharmacology, Shanghai Institute of Physiology, Chinese Academy of Sciences.
Shih
Y L
YL
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002038:Bungarotoxins / Q000378:metabolism / Q000494:pharmacology*; D004351:Drug Resistance; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D011898:Ranidae; D012911:Snakes; D009435:Synaptic Transmission / Q000187:drug effects
D002038:Bungarotoxins