The effects of age and physical activity on cardiac mitochondrial template availability

hronic low intensity physical activity may provide a means of countering the age-associated reductions in cardiac oxidative capacity. The purpose of this study was to examine the effects of aging and physical activity on heart mtDNA template availability. Young (n = 6), mature (n = 12) and senescent (n = 12) C57BL6 mice were used in this study with half the mature and senescent animals being allowed voluntary access to exercise wheels. Cardiac DNA was isolated and the mitochondrial DNA content was assessed by slot blots with a mtDNA specific probe containing 574 base pairs of the cytochrome oxidase I gene. Mitochondrial DNA template availability increased in mouse cardiac tissue with senescence. This was reflected in increases in mitochondrial DNA content per milligram of cardiac tissue and mitochondrial DNA relative to nuclear DNA ratios (P...