NADH-AND NADPH-DEPENDENT REDUCTION OF INDICINE N-OXIDE BY MICROSOMAL CYTOCHROME P-450

Abstract

Indicine N-oxide is reduced to indicine under anaerobic conditions by hepatic microsomal cytochrome P-450. NADH and NADPH are almost equally effective at supporting reduction and their effects are additive with microsomes from untreated rats. NADH dependent reduction is inhibited by 0.5 mM KCN and 0.8 M acetone while NADPH dependent reduction is not effected by 0.5 mM KCN, is stimulated by 0.8 M acetone and increased by phenobarbital pretreatment. A possible explanation for the observations is a form of microsomal cytochrome P-450 which can be reduced by NADH but which does not function during oxidative drug metabolism