Reactive oxygen species induce swelling and cytochrome c release but not transmembrane depolarization in isolated rat brain mitochondria.
1 In this study, we have used isolated brain mitochondria to investigate the effects of superoxide anions (O(2)(-)) on mitochondrial parameters related to apoptosis, such as swelling, potential, enzymatic activity, NAD(P)H, cytochrome c release, and caspase activity. 2 Addition of the reactive oxygen species (ROS) generator KO(2) produced brain mitochondrial swelling, which was blocked by cyclosporin A (CSA), and which was Ca(2+) independent. 3 Calcium induced mitochondrial swelling only at high concentrations and in the presence of succinate. This correlated with the increase in O(2)(-) production detected with hydroethidine in mitochondrial preparations exposed to Ca(2+) and the fact that ROS were required for Ca(2+)-induced mitochondrial swelling. 4 Superoxide anions, but not Ca(2+), decreased citrate synthase and dehydrogenase enzymatic activities and dropped total mitochondrial NAD(P)H levels. 5 Calcium, but not O(2)(-), triggered a rapid loss of mitochondrial potential. Calcium-induced Deltapsi(m) dissipation was inhibited by Ruthenium Red, but not by CSA. 6 Calcium- and superoxide-induced mitochondrial swelling released cytochrome c and increased caspase activity from isolated mitochondria in a CS A-sensitive manner. 7 In summary, superoxide potently triggers mitochondrial swelling and the release of proteins involved in activation of postmitochondrial apoptotic pathways in the absence of mitochondrial depolarization.
Galindo
María F
MF
Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Avda. España s/n, Albacete 02071, Spain.
Jordán
Joaquín
J
González-García
Carmen
C
Ceña
Valentín
V
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D017209:Apoptosis; D001921:Brain / Q000166:cytology; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics; D020169:Caspases / Q000096:biosynthesis / Q000378:metabolism; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D008933:Mitochondrial Swelling / Q000187:drug effects* / Q000502:physiology; D009249:NADP / Q000032:analysis / Q000378:metabolism; D010087:Oxides / Q000493:pharmacokinetics; D010101:Oxygen Consumption / Q000502:physiology; D017680:Potassium Compounds / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000493:pharmacokinetics
D007473:Ion Channels; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010087:Oxides; D017680:Potassium Compounds; D017382:Reactive Oxygen Species; D013481:Superoxides; D009249:NADP; C068440:potassium oxide; D045304:Cytochromes c; D020169:Caspases; D002118:Calcium