Studies on the occurrence of N-demethylase activity in adrenal and hepatic preparations from guinea pigs and rats. The effect of various substances on the magnitude of this activity

Abstract

N-Demethylase activity in guinea pig adrenal and liver homogenates and their 9000 g supernates was demonstrated. In the rat this activity is present in the liver but is absent in the adrenals. The enzymatic activity in livers of male guinea pigs has a pH optimum at 7.5–8.0, whereas this activity in the adrenals demonstrates two pH-activity peaks at 6.75 and 7.25. An identical K m value, 0.17 mM, was demonstrated in liver and adrenal preparations. The administration of diphenylhydantoin, o,p′DDD and DDT to guinea pigs increased hepatic, but not adrenal, N-demethylase. The similarities and differences of the N-demethylase activity in adrenals and livers of guinea pigs are discussed.