The differential effects of superoxide anion, hydrogen peroxide and hydroxyl radical on cardiac mitochondrial oxidative phosphorylation

The involvement of reactive oxygen species (ROS) in cardiac ischemia- reperfusion injuries is well-established, but the deleterious effects of hydrogen peroxide (H2O2), hydroxyl radical (HO center dot) or superoxide anion (O-2(center dot-)) on mitochondrial function are poorly understood. Here, we report that incubation of rat heart mitochondria with each of these three species resulted in a decline of the ADP- stimulated respiratory rate but not substrate- dependent respiration. These three species reduced oxygen consumption induced by an uncoupler without alteration of the respiratory chain complexes, but did not modify mitochondrial membrane permeability. HO center dot slightly decreased F1F0- ATPase activity and HO center dot and O-2(center dot-) partially inhibited the activity of adenine nucleotide translocase; H2O2 failed to alter these targets. They inhibited NADH production by acting specifically on aconitase for O-2(center dot-) and alpha- ketoglutarate dehydrogenase for H2O2 and HO center dot. Our results show that O-2(center dot-), H2O2 and HO center dot act on different mitochondrial targets to alter ATP synthesis, mostly through inhibition of NADH production.