[Response of adenine nucleotide metabolism in the aged rat liver to fasting and succinate injections].

The total adenine nucleotide content in the livers from 24-month-old rats was shown to be by 30% lower than that of 3--4-month-old rat livers. A 24-hr fasting resulted in a decrease of the hepatic ATP levels, ATP/ADP ratios, phosphorylation potentials, adenylate energy charges and action mass ratios of adenylate kinase, crude at the same extents in adult and aged rats as well as in the equal increase of ADP, AMp and Pi levels. Injections of 0.9% NaCl or ammonium succinate to the aged rats (daily for 6 days prior to the experiment) did not affect the hepatic energy metabolism. The effects of potassium succinate was essentially the same as that of the fasting. Any treatment of the aged rats did not increase the total content of adenine nucleotides in the livers. Possible mechanisms of disturbances in adenine nucleotide metabolism upon ageing are discussed.