LACK OF MAJOR CHANGES IN ATPASE ACTIVITY IN MITOCHONDRIA FROM LIVER, HEART, AND SKELETAL-MUSCLE OF RATS UPON AGING

ATP hydrolase activity has been investigated in mitochondria from live r, heart, and skeletal muscle from adult (6 months) and aged (24 month s) rats. No significant changes in total ATPase activity were observed in the three tissues, but the oligomycin sensitivity was slightly dec reased in heart mitochondria of aged rats. The bicarbonate-induced sti mulation of hydrolytic activity was somewhat decreased in mitochondria from aged rats, particularly in liver. No significant change was obse rved in ATPase activity after release of the endogenous inhibitor prot ein, IF1. It is concluded that no activity changes to be directly ascr ibed to the catalytic sector F-1 of the enzyme occur upon ageing, but it cannot be excluded that changes in the membrane sector F-0 occur as a consequence of mtDNA mutations.