AGE-RELATED-CHANGES OF THE MITOCHONDRIAL ENERGY-METABOLISM IN RAT-LIVER AND HEART

The influence of aging on mitochondrial energy metabolism of rat liver and rat heart has been studied by analysis of (i) respiratory rate of succinate-supplemented mitochondria in state III (coupled state in th e presence of ADP + Pi); (ii) the rate of synthesis of ATP in succinat e-supplemented mitochondria; (iii) the ATP hydrolase activity of sonic ated submitochondrial particles. The results indicate a decrease of th e F0F1-ATP synthase activity in mitochondria isolated from both organs of aged (24-month-old) as compared to young (3-month-old) rats which was accompanied by a decrease of immunodetected amount of the beta-F-1 (subunit of the catalytic F-1 sector of F0F1-ATP synthase). These eff ects were more evident in heart than in liver mitochondria. Analysis o f the mitochondrial content of glutathione (GSH), an essential intrace llular antioxidant agent, shows a decrease in mitochondria of both tis sues of aged animals. Exposure of submitochondrial particles to free r adicals, produced either by Co-60 or by respirtory chain (in presence of the inhibitor antimycin A) mimicked the alterations of F0F1 ATP syn thase observed in submitochondrial particles of aged rats. The possibl e relationship between aging process, free radical production and alte ration of mitochondrial oxidative phosphorylation is discussed.