Interplay between superoxide and nitric oxide in aging and diseases.

Free radicals, superoxide and nitric oxide, are important signaling molecules, which mediate numerous physiological functions (phagocytosis, vasorelaxation, etc.). However, regulation errors may lead to free-radical-mediated damaging processes in cells and tissues. In this work, the effects of an interplay between superoxide and NO, which may be responsible for the development of aging and diseases, are considered. We are suggesting that the superoxide-mediated proton leak leading to the inhibition of oxidative phosphorylation and the competition between NO and O2*- in their reactions with cytochrome oxidase can be a cause of mitochondrial aging.