DimethylanilineN-Oxidase and AminopyrineN-Demethylase Activities of Human Liver Tissue

Abstract
1. N-Oxidation of N,N-dimethylaniline and oxidative demethylation of aminopyrine were studied in human liver hornogenates. At their respective pH optima (8·4 for N-oxidase and 7·4 for demethylase) N-oxidase activity was higher than that of demethylase in the majority of biopsies assayed. 2. Neither activity was preferentially influenced by a specific disease process, but both decreased upon severe tissue damage. There was no apparent relationship of either activity with age or sex. 3. Demethylase activities were highest in patients exposed to barbiturates, and increased N-oxidase activity was observed in patients exposed to amphetamines and some tranquilizers.