Characteristics of alpha-glycerophosphate-evoked H2O2 generation in brain mitochondria.
Characteristics of reactive oxygen species (ROS) production in isolated guinea-pig brain mitochondria respiring on alpha-glycerophosphate (alpha-GP) were investigated and compared with those supported by succinate. Mitochondria established a membrane potential (DeltaPsi(m)) and released H(2)O(2) in parallel with an increase in NAD(P)H fluorescence in the presence of alpha-GP (5-40 mm). H(2)O(2) formation and the increase in NAD(P)H level were inhibited by rotenone, ADP or FCCP, respectively, being consistent with a reverse electron transfer (RET). The residual H(2)O(2) formation in the presence of FCCP was stimulated by myxothiazol in mitochondria supported by alpha-GP, but not by succinate. ROS under these conditions are most likely to be derived from alpha-GP-dehydrogenase. In addition, huge ROS formation could be provoked by antimycin in alpha-GP-supported mitochondria, which was prevented by myxothiazol, pointing to the generation of ROS at the quinol-oxidizing center (Q(o)) site of complex III. FCCP further stimulated the production of ROS to the highest rate that we observed in this study. We suggest that the metabolism of alpha-GP leads to ROS generation primarily by complex I in RET, and in addition a significant ROS formation could be ascribed to alpha-GP-dehydrogenase in mammalian brain mitochondria. ROS generation by alpha-GP at complex III is evident only when this complex is inhibited by antimycin.
Tretter
Laszlo
L
Department of Medical Biochemistry, Semmelweis University, Neurobiochemical Group, Hungarian Academy of Sciences and Szentagothai Janos Knowledge Center, Budapest, Hungary.
Takacs
Katalin
K
Hegedus
Vera
V
Adam-Vizi
Vera
V
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology*; D004579:Electron Transport / Q000187:drug effects / Q000502:physiology; D042967:Electron Transport Complex I / Q000187:drug effects / Q000378:metabolism; D014450:Electron Transport Complex III / Q000187:drug effects / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D006168:Guinea Pigs; D006861:Hydrogen Peroxide / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology; D008689:Methacrylates / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013347:Subcellular Fractions; D019802:Succinic Acid / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D000935:Antifungal Agents; D005994:Glycerophosphates; D008689:Methacrylates; D017382:Reactive Oxygen Species; D013844:Thiazoles; D014475:Uncoupling Agents; C032456:antimycin; D009249:NADP; D000968:Antimycin A; C030517:myxothiazol; C029620:alpha-glycerophosphoric acid; D019802:Succinic Acid; D006861:Hydrogen Peroxide; D005993:Glycerolphosphate Dehydrogenase; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III