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. 1975 Oct;251(2):245–270. doi: 10.1113/jphysiol.1975.sp011090

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

V E Dionne, C F Stevens
PMCID: PMC1348425  PMID: 1081139

Abstract

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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