Lipid changes with aging in cardiac mitochondrial membranes.

Mitochondrial membranes were isolated from the myocardium of young (4-month-old) and aged (33-month-old) male Long-Evans rats and compared in terms of cholesterol content and phospholipid and fatty acid composition. In aged rats, as compared to young, the major observations include: markedly higher cholesterol content; increased percentage of sphingomyelin and diphosphatidylglycerol (cardiolipin); in fatty acids, variable changes, with a predominant increase in the 16:0 in most phospholipids except cardiolipin, and sporadic increase in the longer chain (20:0, 24:0) fatty acids in cardiolipin; decreased unsaturation index for most phospholipids but increased for cardiolipin. These results are tentatively interpreted as indicative of an aging-related decrease in fluidity and energy transduction of mitochondrial membrane in the heart of aged rats and may be responsible, in part, for the decrements in cardiac function with aging.