title: Effect of chronic administration of dimethylnitrosamine on the excision of O6-methylguanine from rat liver DNA.
abstract: Rats were exposed chronically to unlabelled N,N-dimethylnitrosamine (25 ppm in the drinking water) then given a single dose of N-[3H]methyl-N-nitrosourea (10 mg/kg body weight). The rates of loss of tritium-labeled 7-methylguanine, O6-methylguanine and 3-methyladenine from the liver DNA in control and dimethylnitrosamine-treated rats were found not to be significantly different. Thus, under the conditions used, inhibition of the O6-methylguanine excision repair system does not seem to be a factor in the induction of liver tumours by chronic DMN application.
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000478:Alkylation; D000818:Animals; D004247:DNA / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects*; D004128:Dimethylnitrosamine / Q000494:pharmacology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008770:Methylnitrosourea / Q000494:pharmacology; D009602:Nitrosamines / Q000494:pharmacology*; D051381:Rats
chemical_list: D009602:Nitrosamines; D006147:Guanine; D008770:Methylnitrosourea; D004247:DNA; D000225:Adenine; D004128:Dimethylnitrosamine