Effect of pretreatment by feeding acetylaminofluorene on methylated purines formed in rat liver DNA after administration of dimethylnitrosamine.

Methylated purines were determined in the liver and kidney DNA of rats that had been pretreated for several weeks by inclusion of 2-acetylaminofluorene in the diet and then given single injections of N,N-dimethylnitrosamine. In comparison ith relevant controls the capacity to remove O(6)-methylguanine from the livers of the pretreated animals was enhanced but there was no evidence for a similar effect in kidney. No market effects of this pretreatment were observed for the removal of 3-methyladenine or 7-methylguanine. The data indicate that an inducing agent may affect the capacity of an animal to repair DNA which is subsequently damaged by another agent of chemically different identity. The mechanisms involved are not clear but potentially these observations have wide implications when organisms are exposed to a variety of chemicals.