Adaptive enzyme responses in the senescent rat: tryptophan peroxidase and tyrosine transaminase

Abstract

Two of the adaptive enzymes of liver, tryptophan peroxidase and tyrosine transaminase, have been determined in mature (12–13 months old) and senescent (24–26 months old) rats. Basal levels of the two enzymes, the increase of tryptophan peroxidase after substrate administration, and of both tryptophan peroxidase and tyrosine transaminase after adrenal cortical hormone (hydrocortisone) have been studied. In both groups of animals the mean enzyme activities were the same in all instances. The data fail to indicate that senescence is accompanied by a biochemically demonstrable impairment of the mechanisms involved in adaptive enzyme formation.