Abstract
Summary
Changes in the adenine nucleotide dephosphorylating system in the gastrocnemius muscle of aging male rats have been studied. The Mg-activated ATP-ase activity showed a pronounced fall from young to very old (senile) age in both the Sprague-Dawley and the CFN strains. However, in the former strain, old animals, typically exhibiting markedly greater losses in muscle mass and concomitant muscular dystrophy, also showed a greater decline in this enzyme on a unit muscle mass and even more so on an absolute body mass basis, than did the old CFN rats. In both strains, however, actomyosin (pH 9.0) ATP-ase as well as ATP content showed no significant changes from young to very old age. The role of the Mg-activated ATP-ase enzyme in energizing of skeletal muscle contraction and its possible significance in the physiology of senescence are discussed.
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