Voltage dependence of agonist effectiveness at the frog neuromuscular junction: resolution of a paradox.

作者：Vincent E. Dionne, Charles F. Stevens · 发表于：The Journal of Physiology · 年份：1975 · DOI：10.1113/jphysiol.1975.sp011090 · 被引用次数：186 · 研究领域：Neuroscience and Neural Engineering、Mechanical and Optical Resonators、Microfluidic and Bio-sensing Technologies

1. End-plate currents produced by nerve-released acetylcholine and iontophoretically applied acetylcholine and carbachol have been recorded from voltage-clamped frog cutaneous pectoris neuromuscular junctions made visible with Nomarski differential interference contrast optics. 2. The effectiveness of agonists - that is, the end-plate conductance change produced by a given dose-has been determined as a function of post-junctional membrane potential. 3. As the post-junctional membrane potential is made more negative, nerve-released acetylcholine becomes less effective whereas iontophoretically-applied agonists become more effective. 4. This voltage dependence of agonist effectiveness is mediated neither by end-plate current iontophoresis of agonist into the cleft nor through electric field effects on the esterase. 5. Influences of membrane potential on the opening and closing of end-plate channel gates can account quantitatively for the voltage-dependent effectiveness of both nerve-released and iontophoretically applied agonist.