Induction of hepatic mixed function oxidases in senescent rodents—II. Effect of polychlorinated biphenyls

Senescent alterations in the ability of the drug-metabolizing system of rat liver to respond to treatment with the potent mono-oxygenase inducer Aroclor 1254, a complex mixture of polychlorinated biphenyls, was analyzed. The contents of hepatic microsomal cytochrome P 450, NADPH cytochrome c reductase, and lipid were measured as were several coordinated mixed function oxidase activities. The peptide composition was also examined by slab gel electrophoresis. The senescent rodents responded as well or better than younger animals to induction with polychlorinated biphenyls, in certain cases restoring the “young” mono-oxygenase system. Thus, the old rats exhibit no age-related impairment in their response capacity to inducers of hepatic drug metabolism.