FUNCTIONAL-STATE OF THE XENOBIOTIC BIOTRANSFORMATION SYSTEM IN ANIMALS INTOXICATED WITH DIPHENYLAMINE OR N-NITROSODIPHENYLAMINE

The system for biotransformation of xenobiotics was studied in male wh ite rats given a single oral dose of diphenylamine (DPA) or N-nitrosod iphenylamine (NDPA). NDPA induced consistent and equivalent functional changes in both steps of metabolism of the toxicants. The total level s of cytochrome P-450 and the activity of NADPH-cytochrome P-450 reduc tase increased The activity of microsomal glutathione S-transferase co nsiderably increased Several isoenzymes of the multifunctional family of rat liver cytosol glutathione S-transferases were induced, and glut athione reductase was activated In contrast to NDPA, intoxication with DPA affected only the second stage of biotransformation of xenobiotic s and activated the membrane-associated and soluble glutathione S-tran sferases. Both toxicants increased the content of non-protein sulfhydr yl groups. The difference in the responses of the system of biotransfo rmation of xenobiotics to the tested compounds is due to the addition of the N-nitroso group to DPA.