Mg2+ block and inward rectification of mechanosensitive channels in Xenopus oocytes

George Wu, Don W. McBride, Owen P. Hamill

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The effects of Mg2+ on single mechanosensitive (MS) channel currents recorded from Xenopus oocytes were studied using cell-attached and inside-out patch configurations. Mg2+ both permeates and blocks MS channels. Under symmetrical ionic conditions, the blocking effects of Mg2+ can be described by a Hill coefficient of 0.9 at ±100 mV and IC50s of 0.12 mM (-100 mV) and 0.60 mM at (+100 mV). Although block by intracellular Mg2+ may contribute to inward MS channel rectification, significant current rectification is retained even under symmetrical KCl concentrations and in the complete absence of Mg2+. The observed voltage dependencies of the IC50 for Mg2+ block and the K(m) for K+ current saturation indicate asymmetries in the MS channel pore. In addition, the absence of K+ self block and anomalous mole fraction effects with K+/Tl+ mixtures indicate a single site pore model.

Original languageEnglish (US)
Pages (from-to)572-574
Number of pages3
JournalPflugers Archiv European Journal of Physiology
Volume435
Issue number4
DOIs
StatePublished - Jan 1 1998

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Keywords

  • Mechanosensitive channels Mg
  • Rectification
  • Xenopus oocyte

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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