Age-related changes in the redox status of rat muscle cells and their role in enzyme-aging.

The redox status of three biological components capable of undergoing oxidation-reduction reactions, glutathione, NAD and NADP, were determined in muscle tissues of young and old rats. A considerable increase in the relative concentration of the oxidized form, at the expense of the reduced one was found in the old tissue reflecting a significantly less reducing environment than in young cells. The effects of varying the ratio of reduced/oxidized glutathione in vitro on the activity of the enzyme glyceraldehyde-3-phosphate dehydrogenase extracted from young and old animals were compared. It was found that concentrations of GSSG as found in old muscle tissue do not affect enzyme samples extracted from young muscle. The accumulation of oxidized glutathione observed in old cells does not, therefore, directly cause the age-related activity loss of this enzyme.