α-Conotoxin GI produces tetanic fade at the rat neuromuscular junction

摘要: Abstract The ability of the marine snail toxin, α-conotoxin GI, to produce blockade singly evoked twitches and tetanic train-of-four fade has been determined in isolated rat hemidiaphragm preparation. Results were compared those obtained with a reversible (vecuronium) an irreversible (α-bungarotoxin) nicotinic acetylcholine antagonist have interpreted terms relative effects on post- prejunctional receptors at neuromuscular junction. α-Conotoxin GI (0.5–2 μM) produced concentration-dependent, readily reversible, decrease peak amplitude single 50 Hz tetani, increase fade. was consistently 2–3-fold more potent than vecuronium respect all measured tension parameters. Both approximately 2-fold producing blocking contractions twitches. In contrast both vecuronium, α-bungarotoxin (0.13 reduced tetani same extent without appearance large degree or Based comparison vitro time course block twitches, trains-of-four, we conclude that pre- postjunctional activity this respect, resembles clinically used competitive drugs rather snake α-neurotoxins.