[Accumulation of methylated purines in the liver and large intestine DNA of rats following repeated administrations of 1,2-dimethylhydrazine].

Experiments on rats given weekly injections of the intestinal carcinogen 1,2-dimethylhydrazine (DMH) have shown that liver and colon DNA accumulated 7-methylguanine and some methylated adducts of adenine. In addition, DNA of liver tissues and crypt bottom cells accumulated O6-methylguanine. The conclusion is drawn on the role of its persistence in DNA of stem enterocytes in the initiation of colonic carcinogenesis. The mechanism of liver tissue resistance to the carcinogenic effect of DMH is discussed.