Use of mu-conotoxin GIIIA for the study of synaptic transmission at the frog neuromuscular junction.
We have looked at the effect of synthetic mu-conotoxin GIIIA, a selective blocker of muscle Na channels, on various parameters of synaptic transmission at the frog sartorius nerve-muscle preparation. We found that 5 microM mu-conotoxin consistently blocked muscle action potentials, but had no effect on nerve action potentials. The toxin also had no effect on the amplitude or frequency of miniature endplate potentials (MEPPs), on the amplitude or time course of endplate potentials (EPPs), or on stimulation-induced changes in EPP amplitude. The lack of an effect of synthetic mu-conotoxin GIIIA on transmitter release makes this toxin an invaluable tool in the study of neuromuscular transmission under conditions of normal levels of release.
Sosa
M A
MA
Veterans Administration Medical Center, Gainesville, FL.
Zengel
J E
JE
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D020916:Conotoxins; D008978:Mollusk Venoms / Q000494:pharmacology*; D009132:Muscles / Q000187:drug effects / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010525:Peripheral Nerves / Q000187:drug effects / Q000502:physiology; D011894:Rana pipiens; D015222:Sodium Channels / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*
D020916:Conotoxins; D008978:Mollusk Venoms; D010456:Peptides, Cyclic; D015222:Sodium Channels; C046101:conotoxin GIII