title: Mitochondrial sites of hydrogen peroxide production in reperfused rat kidney cortex.
abstract: Electron transport and production of O2-/H2O2 by the NADH dehydrogenase flavin-semiquinone (FMNH.) and ubisemiquinone (UQH.) were studied in a model of in vivo ischemia-reperfusion in rat kidney. H2O2 production rates were assessed in isolated mitochondria using either succinate, with and without antimycin, or malate-glutamate, with and without rotenone. Respiratory activities of isolated mitochondria and activity of NADH- and succinate-cytochrome c reductase and of NADH- and succinate-dehydrogenase in submitochondrial particles were measured to evaluate the electron flux throughout respiratory carriers. The mitochondrial H2O2 production rate was approximately 1.5- and 4-times increased in ischemic and ischemic-reperfused kidneys, respectively. Ischemia caused a marked decrease in the electron transport throughout the NADH-UQ segment with no significant changes either in the NADH dehydrogenase activity or in the electron flux trough the succinate-cytochrome oxidase segment. Reperfusion did not further affect the NADH-ubiquinone segment but markedly inhibited the succinate-supported oxygen consumption, succinate-cytochrome c reductase and succinate dehydrogenase activity. Our results show a redistribution of the electron flux with an increased rate of superoxide anion/hydrogen peroxide production at NADH dehydrogenase in mitochondria subjected to ischemia only. After 10 min reperfusion an impairment of the electron flow at succinate-cytochrome c segment is established and hydrogen peroxide production by UQH. increases up to maximal values becoming the major source of superoxide anion/hydrogen peroxide.
authors.affiliation: Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
authors.forename: B
authors.initials: B
authors.lastname: González-Flecha
authors.forename: A
authors.initials: A
authors.lastname: Boveris
mesh_terms: D000818:Animals; D004579:Electron Transport; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism*; D007672:Kidney Cortex / Q000098:blood supply* / Q000648:ultrastructure; D007700:Kinetics; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar; D015424:Reperfusion; D013367:Submitochondrial Particles / Q000378:metabolism; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D013481:Superoxides; D006861:Hydrogen Peroxide; D013384:Succinate Cytochrome c Oxidoreductase; D013385:Succinate Dehydrogenase; D009245:NADH Dehydrogenase