@article {Rikans574, author = {L E Rikans and B A Notley}, title = {Age-related changes in hepatic microsomal drug metabolism are substrate selective.}, volume = {220}, number = {3}, pages = {574--578}, year = {1982}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Microsomes were isolated from livers of male Fischer 344 rats at 3 to 5, 14 to 15 and 24 to 25 months of age for the determination of monooxygenase components and drug metabolism activities. Microsomal cytochrome P-450, cytochrome b5, NADPH-cytochrome c reductase activity and phospholipid were decreased in middle-aged and old rats compared with young-adult rats, but the enzymatic reduction of microsomal cytochrome P-450 was unchanged. Drug metabolism activities both decreased and increased as a consequence of aging, depending upon the substrate used. Differences were observed between young-adult and old rats in the CO maximum of reduced microsomal cytochrome P-450, in microsomal fatty acid composition and in the amounts of microsomal polypeptides having molecular weights of 52,500 and 53,000. The substrate selectivity of the age-related alterations in hepatic microsomal drug metabolism may be due to qualitative changes in the cytochrome P-450 and phospholipid components of the monooxygenase system.}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/220/3/574}, eprint = {https://jpet.aspetjournals.org/content/220/3/574.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }