ABSTRACT
Mitochondria are an important intracellular source of reactive oxygen species, although alternative sources in other organelles and the cytoplasm are present in cells. Based upon the large body of work, it is likely that reactive oxygen species participate in aging and aging-associated pathology. However, whether mito chondrial or other sources play a more important role in aging is an unsolved matter. In both compartments, the mitochondrial and the cytosol enzymatic and nonenzymatic systems are available, which apparently serve to decrease the reac tive oxygen species steady-state concentration. Nevertheless, DNA, proteins, and lipids are subject to oxidative damage that increases with age (1-7).
