Modification of ionic currents underlying action potentials in mouse nerve terminals by the thiol-oxidizing agent diamide.
The effect of diamide, a thiol-oxidizing agent, was tested using electrophysiological techniques to determine whether its ability to alter neuromuscular transmission in vitro could be attributed to alterations of ion channels controlling neuronal excitability and/or acetylcholine release. In mouse triangularis sterni preparations, diamide transiently increased the evoked release of acetylcholine and then blocked release. Extracellular recording of perineural waveforms associated with neuronal action potentials at motor nerve terminals showed that diamide reduced the waveforms associated with the delayed rectifier K+ current, a Ca2+ current and a Ca(2+)-activated K+ current (IK,Ca). Inhibition of quantal transmitter release was not associated with failure of action potentials to invade nerve terminals. Thus, diamide modifies the ionic currents underlying the nerve terminal action potential, some of these changes probably account for the complex effects of diamide on quantal transmission.
Braga
M F
MF
Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, UK.
Rowan
E G
EG
Harvey
A L
AL
D000109:Acetylcholine / Q000378:metabolism*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003958:Diamide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008297:Male; D051379:Mice; D009469:Neuromuscular Junction / Q000187:drug effects*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
D007473:Ion Channels; D013439:Sulfhydryl Reagents; D003958:Diamide; D000109:Acetylcholine