THE CA2-INDUCED PORE OPENING IN MITOCHONDRIA ENERGIZED BY SUCCINATE-FERRICYANIDE ELECTRON-TRANSPORT()

The oxygen dependence of the mitochondria permeability transition pore was under study in non-respiring rat liver mitochondria. Oxygen in th e medium was depleted by saturation of the incubation medium with N-2 and spontaneously by mitochondrial respiration followed by the additio n of glucosel glucose oxidase. After the anaerobic state had been reac hed, ferricyanide has been added to support succinate-driven energizat ion in the absence of oxygen. In the other set of the experiments KCN was added to block operation of the respiratory chain under aerobic co nditions. Again, ferricyanide was added as an electron acceptor. Super oxide dismutase was added to trap superoxide anion radicals. Under eit her hypoxic conditions or in the presence of cyanide, calcium ions mer e shown to induce the permeability transition. The concentration of Ca 2+ required was lower than under conditions of active respiration. In both cases, the transition was prevented by cyclosporine A. (C) 1997 F ederation of European Biochemical Societies.