Demonstration of functional heterogeneity of hepatic uridine diphosphate glucuronosyltransferase activities after administration of 3-methylcholanthrene and phenobarbital to rats

Abstract

After the administration of 3-methylcholanthrene to adult male rats, activities of hepatic UDP-glucuronosyltransferase (EC 2.4.1.17) towards 6 from a group of 12 substrates were stimulated by 250-350%. Activities towards the remaining 6 substrates were unaffected. Conversely, after phenobarbital administration, activities formerly stimulated by 3-methylcholanthrene remained unchanged, and the other 6 activities were stimulated by 160-280%. The relationship of these 2 groups of transferase activities to other evidence suggesting the same heterogeneity of the enzyme is discussed.