The alpha-neurotoxin erabutoxin b causes fade at the rat end-plate.
d-Tubocurarine and the alpha-neurotoxins from snake venom are antagonists at the nicotinic acetylcholine receptor. It is well established that d-tubocurarine causes fade in neuromuscular transmission during repetitive nerve stimulation but paradoxically there are many reports which indicate that the alpha-neurotoxins do not cause such fade. We found that high concentrations of erabutoxin b (100-150 nM) from the venom of Laticauda semifasciata did not cause much fade in the rat diaphragm preparation. However, low concentrations of toxin (5 nM) caused severe fade which was similar to the effects of d-tubocurarine. The data suggest that fade may be caused by toxin binding to a high-affinity site on the postsynaptic acetylcholine receptor.
Bradley
R J
RJ
Department of Psychiatry, School of Medicine, University of Alabama, Birmingham 35294.
Edge
M T
MT
Chau
W C
WC
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004546:Elapid Venoms / Q000494:pharmacology*; D004558:Electric Stimulation; D004870:Erabutoxins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009045:Motor Endplate / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D051381:Rats; D012132:Respiratory Muscles / Q000187:drug effects / Q000502:physiology; D014403:Tubocurarine / Q000494:pharmacology
D004546:Elapid Venoms; D004870:Erabutoxins; C032917:erabutoxin b; D014403:Tubocurarine