Opening of the mitochondrial permeability transition pore by uncoupling or inorganic phosphate in the presence of Ca 2+ is dependent on mitochondrial-generated reactive oxygen species

Abstract

In this study, we show that mitochondrial membrane permeability transition in Ca 2+-loaded mitochondria treated with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) or inorganic phosphate (P i) is preceded by enhanced production of H 2O 2. This production is inhibited either by ethylene glycol-bis( b-aminoethyl ether) N, N, N′, N′-tetraacetic acid (EGTA) or Mg 2+, but not by cyclosporin A. Permeability transition is prevented either by EGTA, catalase or dithiothreitol, suggesting the involvement of Ca 2+, H 2O 2 and oxidation of membrane protein thiols in this mechanism. When mitochondria are incubated under anaerobiosis, no permeabilization or H 2O 2 production occurs. Based on these results we conclude that mitochondrial permeability transition induced by P i or FCCP-uncoupling is dependent on mitochondrial-generated reactive oxygen species.