Nitric oxide inhibits mitochondrial NADH:ubiquinone reductase activity through peroxynitrite formation.
This study was aimed at assessing the effects of long-term exposure to NO of respiratory activities in mitochondria from different tissues (with different ubiquinol contents), under conditions that either promote or prevent the formation of peroxynitrite. Mitochondria and submitochondrial particles isolated from rat heart, liver and brain were exposed either to a steady-state concentration or to a bolus addition of NO. NO induced the mitochondrial production of superoxide anions, hydrogen peroxide and peroxynitrite, the latter shown by nitration of mitochondrial proteins. Long-term incubation of mitochondrial membranes with NO resulted in a persistent inhibition of NADH:cytochrome c reductase activity, interpreted as inhibition of NADH:ubiquinone reductase (Complex I) activity, whereas succinate:cytochrome c reductase activity, including Complex II and Complex III electron transfer, remained unaffected. This selective effect of NO and derived species was partially prevented by superoxide dismutase and uric acid. In addition, peroxynitrite mimicked the effect of NO, including tyrosine nitration of some Complex I proteins. These results seem to indicate that the inhibition of NADH:ubiquinone reductase (Complex I) activity depends on the NO-induced generation of superoxide radical and peroxynitrite and that Complex I is selectively sensitive to peroxynitrite. Inhibition of Complex I activity by peroxynitrite may have critical implications for energy supply in tissues such as the brain, whose mitochondrial function depends largely on the channelling of reducing equivalents through Complex I.
Riobó
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NA
Laboratory of Oxygen Metabolism, University Hospital, University of Buenos Aires, Córdoba 2351, 1120, Buenos Aires, Argentina. nataliariobo@hotmail.com
Clementi
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E
Melani
M
M
Boveris
A
A
Cadenas
E
E
Moncada
S
S
Poderoso
J J
JJ
D000818:Animals; D001921:Brain / Q000187:drug effects; D004579:Electron Transport / Q000187:drug effects; D042967:Electron Transport Complex I; D042963:Electron Transport Complex II; D005260:Female; D006321:Heart / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D015151:Immunoblotting; D008099:Liver / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D008929:Mitochondria, Heart / Q000187:drug effects; D009097:Multienzyme Complexes / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D010088:Oxidoreductases / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D009097:Multienzyme Complexes; D013386:Succinates; D009243:NAD; D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D013384:Succinate Cytochrome c Oxidoreductase; D013482:Superoxide Dismutase; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I