Effect of phenobarbital and 3-methylcholanthrene on the hepatic microsomal metabolism of N-nitrosodimethylamine, N-nitrosomethylbutylamine and N-nitrosomethylbenzylamine.

The effect of phenobarbital (PB) and 3-methylcholanthrene (MC) pretreatment on dealkylations of N-nitrosodimethylamine (NDMA), N-nitrosomethylbutylamine (NMBuA) and N-nitrosomethylbenzylamine (NMBeA) was investigated in rat hepatic microsomes. PB increased the demethylation and the debutylation of NMBuA and the debenzylation of NMBeA. MC increased the debutylation of NMBuA and the debenzylation of NMBeA. However, MC decreased the demethylation of NMBeA. The demethylation of NDMA was not changed by the pretreatment of the inducers. These results suggest that the dealkylations of these nitrosamines are catalyzed by several enzymes, which probably depend on different cytochrome P-450 species.