Effect of simulated hypoxia (7620 m, 6 h) on hepatic microsomal drug metabolising enzymes activity in rats given ethanol and vitamin A.

The hepatic MFO activity has been studied in rats exposed to acute hypoxia given single dose of ethanol (3 g/kg body weight) alone or along with 10,000 I.U. of vitamin A. The cytochrome P-450 was found to be depressed on ethanol administration in rats. Hypoxic exposure of rats given ethanol with or without vitamin A, however, restored the depressed cytochrome P-450 activity. Cytochrome-c-reductase, on the other hand, was increased on administration of ethanol with or without vitamin A supplementation. Exposure to hypoxia did not have any additional effect on cytochrome c-reductase activity. Aminopyrine-N-demethylase was depressed on ethanol administration. Vitamin A administration further depressed this enzyme. Hypoxic exposure, however, did not restore this enzyme level. Aniline hydroxylase was not affected by ethanol administration, vitamin A supplementation and hypoxic exposure. Thus, mixed function oxidase system appears to be differently affected on ethanol administration, vitamin A supplementation and hypoxic exposure suggesting that these effectors have different loci of interaction in microsomal structure and/or in its micromileau of cofactors.