title: Dietary ascorbic acid and hepatic mixed function oxidase activity in the guinea pig.
abstract: Studies were carried out to characterize the response of hepatic mixed function oxidase (MFO) activity to chronic ascorbic acid deficiency and excessive ascorbic acid intake in the guinea pig. When guinea pigs were fed excessive ascorbic acid, there was a small increase in hepatic cytochrome P-450 which was unaccompanied by any alteration in drug-metabolizing enzyme activity. Similarly, induction of MFO activity by phenobarbital was not modified by excessive ascorbic acid administration. Chronic ascorbic acid deficiency resulted in depressed metabolism of aniline, aminopyrine, ethoxycoumarin and benzphetamine, but not of ethylmorphine, in comparison with animals fed diets containing control and/or excessive amounts of ascorbic acid. In contrast to the metabolism of all drugs studied, the 7 alpha-hydroxylation of cholesterol was depressed by both inadequate and excessive vitamin C intake, demonstrating the unique sensitivity of cholesterol 7 alpha-hydroxylase to dietary ascorbate.
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D001206:Ascorbic Acid Deficiency / Q000201:enzymology; D001589:Benzphetamine / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D006168:Guinea Pigs; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology
chemical_list: D001589:Benzphetamine; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D001205:Ascorbic Acid; D010634:Phenobarbital