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. 1980 Jun 1;75(6):693–708. doi: 10.1085/jgp.75.6.693

The effects of external Ca++ and Mg++ on the voltage sensitivity of desensitization in Electrophorus electroplaques

PMCID: PMC2215267  PMID: 7391813

Abstract

Desensitization onset was studied in voltage-clamped Electrophorus electroplaques during prolonged exposure to bath-applied carbamylcholine. The time-course of desensitization was described by a first-order rate constant kappa obs, which increased exponentially with membrane hyperpolarization from -20 to -90 mV. When Ca++ was increased from 2 to 10 mM, the voltage sensitivity of kappa obs decreased; kappa obs decreased for voltages more negative than -40 mV, and increased slightly at voltages more positive than -40 mV. 10 mM Mg++ had a less pronounced effect and the voltage sensitivity of kappa obs was unchanged. The equilibrium level of desensitization, estimated from the carbamylcholine-dependent conductance which remained after desensitization was apparently complete, also increased with hyperpolarization.

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Selected References

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