Water and ion distributions in myocytes cultured under oxidative stress mimic changes found in the process of aging

Element concentrations and local water content were measured in cytoplasm, nuclei, mitochondria and lipofuscin granula (LG) of isolated cardiac myocytes of the rat. Cells were cultured for 14 days under either 5%, 20% or 40% ambient oxygen concentration. LG were found to contain less cations and more phosphorous than mitochondria, which might be related to their lower protein and higher lipid content. Under oxidative stress, dehydration of mitochondria occurred, while their cation content remained constant. This is the same pattern of changes as found in cells in situ of aging rats. Therefore, it is concluded that peroxidative damage via oxygen derived free radicals is the reason for the mitochondrial water loss in the process of aging.