Energy-dependence exchange of K+ in heart mitochondria. K+ efflux. |
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Authors: | E Chávez D W Jung G P Brierley |
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Institution: | Department of Physiological Chemistry, College of Medicine, Ohio State University, Columbus, Ohio 43210 U.S.A. |
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Abstract: | The efflux 42K+ from isolated beef heart mitochondria under conditions of near steadystate K+ is increased by repiration and is sensitive to uncouplers and to exogenous Mg2 The respiration-dependent efflux is strongly activated by inorganic phosphate in the presence of external K+, but not Na+, and is inhibited by oxidative phosphorylation. Low concentrations of mersalyl also activate respiration-dependent efflux of 42K+ in the absence of net alteration in matrix K+. Acetate in the presence of mersalyl brings about net accumulation of K+ with retention of internal 42K+. The results are consistent with a model in which nearly constant matrix K+ is maintained by the regulated interplay between a K+ uniport (which is responsive to membrane potential and which is the pathway for K+ influx) and a exchanger (which responds to the transmembrane pH differential and which is the pathway for net K+ efflux). |
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