Ion transport in rat liver mitochondria: the effect of the incubation medium osmolarity

Abstract

A decrease in the incubation medium osmolarity from 320 to 120 mosM reverses the pH dependence of K + efflux from rat liver mitochondria. The K + efflux is no longer inhibited by oligomycin and a free radical scavenger butylhydroxytoluene. At 320 mosM, the addition of carbonyl cyanide 3-chlorophenylhydrazone (CCCP) accelerates the K + efflux, while EGTA inhibits it. At 120 mosM these CCCP and EGTA effects are reversed. In either case the K + efflux is inhibited by Mg 2+. The decrease in osmolarity changes the ruthenium red-insensitive Ca 2+ efflux in the same manner. It has thus been shown that the modification of the mitochondrial structure by changing the incubation medium osmolarity results in a qualitative alteration of the systems regulating the K + and Ca 2+ effluxes. Mitochondria Ion transport ATPase Osmolarity Free radical reaction