Effect of Spironolactone and Ethylestrenol on Benzo(a)pyrene Hydroxylase (EC 1.14.1.1) and Other Chemical Constituents of Hepatic Microsomes

Abstract

In rats, spironolactone and ethylestrenol, like phenobarbital, enhance the NADPH-dependent hydroxylation of benzo(a)pyrene in the hepatic microsomal plus supernatant fraction and increase liver weight and microsomal phospholipid content as well as NADPH cytochrome c reductase and diaphorase activities, but only ethylestrenol and phenobarbital influence the microsomal protein content and cytochrome P-450 level.Neither spironolactone, ethylestrenol, nor phenobarbital affects NADH cytochrome c reductase and diaphorase activities, and only phenobarbital alters the cytochrome b5 level.These findings indicate that, while both the steroids and phenobarbital stimulate microsomal mixed-function oxidation, there are qualitative and quantitative differences between their action.