DIFFERENT EFFECTS OF CAFFEINE ON CARCINOGEN BIOTRANSFORMATION IN RAT-LIVER MICROSOMES - DEPENDENCE ON INDUCTION STATES

To study the effects of caffeine on carcinogen biotransformation, the effects of caffeine on N-nitrosodimethylamine demethylase were studied in liver microsomes from control, phenobarbital (PB)-, and 3-methylch olanthrene (3-MC)-pretreated rats. Caffeine significantly decreased N- nitrosodimethylamine demethylase in control microsomes whereas it sign ificantly enhanced the enzyme activity in 3-MG induced microsomes. No apparent effect was observed in PB-induced microsomes. Additionally, c affeine did not show any significant effects on aminopyrine N-demethyl ase and aniline hydroxylase in control microsomes but significantly in hibited those reactions in 3-MC-induced microsomes. The effects of caf feine on the biotransformation of xenobiotics including carcinogens ar e different depending on induction states. Bioactivation of carcinogen s appears to be enhanced in the presence of caffeine under certain cir cumstances.