[DNA alkylation during endogenous synthesis of N-nitrosodimethylamine]

The simultaneous administration of 14C-dimethylamine and sodium nitrite to rat stomach produces the formation of O6-methylguanine and 7-methylguanine in the liver DNA as a result of the endogenic synthesis of N-nitrosodimethylamine (NDMA). Methylation of DNA was also observed in the rat kidney and lung. Alkylation of O6-position of guanine and removal of its methylated product from the DNA occurred in the liver to a greater extent than in the other NDMA target organs. Pretreatment of rats with sodium nitrite increased the alkylation of liver DNA caused by endogenic synthesis of NDMA. The formation of alkylated products in DNA may be used as a marker for the endogenic formation of NDMA from precursors.