title: Proton leak induced by reactive oxygen species produced during in vitro anoxia/reoxygenation in rat skeletal muscle mitochondria.
abstract: Superoxide anion generation and the impairment of oxidative phosphorylation yield were studied in rat skeletal muscle mitochondria submitted to anoxia/reoxygenation in vitro. Production of superoxide anion was detected after several cycles of anoxia/reoxygenation. Concomitantly, a decrease of state 3 respiration and phosphorylation yield (ADP/O) were observed. The latter resulted from a proton leak. The presence of palmitic acid during anoxia/reoxygenation cycles led to a dose-dependent inhibition of superoxide anion production together with a partial protection of the ADP/O ratio measured after anoxia/reoxygenation. The ADP/O decrease was shown to be due to a permeability transition pore-sustained proton leak, as it was suppressed by cyclosporine A. The permeability transition pore activation was induced during anoxia/reoxygenation by superoxide anion, as it was cancelled by the spin trap (POBN), which scavenges superoxide anion and by palmitic acid, which induces mitochondrial uncoupling. It can be proposed that the palmitic acid-induced proton leak cancels the production of superoxide anion by mitochondria during anoxia/reoxygenation and therefore prevents the occurrence of the superoxide anion-induced permeability transition pore-mediated proton leak after anoxia/reoxygenation.
authors.affiliation: Laboratory of Bioenergetics, Oxygen Biochemistry Centre, University of Liege, Sart Tilman B6c, 4000 Liege, Belgium.
authors.forename: Rachel
authors.initials: R
authors.lastname: Navet
authors.forename: Ange
authors.initials: A
authors.lastname: Mouithys-Mickalad
authors.forename: Pierre
authors.initials: P
authors.lastname: Douette
authors.forename: Claudine M
authors.initials: CM
authors.lastname: Sluse-Goffart
authors.forename: Wieslawa
authors.initials: W
authors.lastname: Jarmuszkiewicz
authors.forename: Francis E
authors.initials: FE
authors.lastname: Sluse
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D016572:Cyclosporine / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D066298:In Vitro Techniques; D017136:Ion Transport; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000502:physiology; D000083162:Mitochondrial Permeability Transition Pore; D009589:Nitrogen Oxides / Q000737:chemistry; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D019308:Palmitic Acid / Q000494:pharmacology; D011522:Protons; D011725:Pyridines; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009589:Nitrogen Oxides; D011522:Protons; D011725:Pyridines; D017382:Reactive Oxygen Species; C043438:alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; D013481:Superoxides; D019308:Palmitic Acid; D016572:Cyclosporine; D010100:Oxygen