Aniline hydroxylation and 7-ethoxycoumarin O-deethylation activities in solubilized and partially resolved liver cytochromes P-450 from ethanol-fed rats

Abstract

Chronic ethanol administration in female rats enhances the apparent molar activity of liver microsomes for aniline hydroxylation and 7-ethoxycoumarin O-deethylation. Microsomal cytochromes P-450 from ethanol-fed and control rats have been solubilized and partially resolved in six fractions by anion-exchange chromatography. Induction of aniline hydroxylase activity by ethanol was associated with marked increases in the turnover numbers of the more basic cytochrome P-450 containing fractions in a reconstituted aniline hydroxylation system. Cytochrome P-450, exhibiting by far the highest 7-ethoxycoumarin O-deethylase activity, was eluted in a relatively acidic fraction; its turnover number with 7-ethoxycoumarin after ethanol consumption, however, did not differ significantly from that of the corresponding fraction from control microsomes. These observations suggest that induction of liver microsomal mixed function oxidases by ethanol may reflect the contribution of more than one cytochrome P-450 isozyme.