Inhibitory Effect of Carbon Monoxide on the Hydroxylation of Testosterone by Rat Liver Microsomes

Abstract

Abstract The metabolism of testosterone to 6β-, 7α-, and 16α-hydroxytestosterone by rat liver microsomes is inhibited by carbon monoxide. The degree of inhibition of the three hydroxylation reactions differs. The ratios of CO to O2 needed for 50% inhibition of the 16α-, 6β-, and 7α-hydroxylation of testosterone are 0.93, 1.54, and 2.36, respectively. Studies on the light reversibility of the CO inhibition revealed that light at 450 mµ decreases the inhibitory effect of CO on the 6β-, 7α-, and 16α-hydroxylation reactions to a greater extent than light at other wave lengths. The results obtained suggest that one or more CO-binding cytochromes function in the hydroxylation of testosterone by rat liver microsomes.