[The functional status of the xenobiotic biotransformation system in poisoning animals with diphenylamine and N-nitrosodiphenylamine].

The state of the xenobiotic biotransformation system has been studied after a single per os administration of diphenylamine (DPA) and N-nitrosodiphenylamine (NDPA) to male albino rats. Intoxication of animals with NDPA induced unidirectional and similar changes in the functional states of the both stages of the xenobiotic metabolism. There was an increase in the total content of cytochrome P-450 and the activity of NADPH-cytochrome P-450 reductase as well as a marked elevation of activity of microsomal glutathione S-transferase. This was paralleled with the induction of activity of individual isoenzymes of the multifunctional family of rat liver cytosol glutathione S-transferases and increased activity of glutathione reductase. Unlike NDPA, DPA affected only the second stage of the xenobiotic biotransformation by stimulating the activity of both membrane-bound and soluble glutathione S-transferases. In both cases the intoxication was attended by an increase in the number of SH-groups unbound to the protein. It was assumed that the different response of the xenobiotic biotransformation system to DPA and NDPA may be due to the appearance of a N-nitroso group in the NDPA molecule.