Article ID Journal Published Year Pages File Type
1938273 Biochemical and Biophysical Research Communications 2007 6 Pages PDF
Abstract

To explore the potential function of the BK channel in the inner mitochondrial membrane under physiological and hypoxic conditions, we used on-mitoplast and whole-mitoplast patches. Single BK channels had a conductance of 276 ± 9 pS under symmetrical K+ solutions, were Ca2+- and voltage-dependent and were inhibited by 0.1 μM charybdotoxin. In response to hypoxia, BK increased open probability, shifted its reversal potential (9.3 ± 2.4 mV) in the positive direction and did not change its conductance. We conclude that (1) the properties at rest of this mitoplast K+ channel are similar to those of BK channels in the plasma membrane; (2) hypoxia induces an increase, rather than a decrease (as in the plasmalemma), in the open probability of this K+ channel, leading to K+ efflux from the mitochondrial matrix to the outside. We speculate that this increase in K+ efflux from mitochondria into the cytosol is important during hypoxia in maintaining cytosolic K+.

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