title: Metabolism of dimethylnitrosamine and subsequent removal of O6-methylguanine from DNA by isolated rat hepatocytes.
abstract: Freshly prepared isolated hepatocytes were shown to metabolize dimethylnitrosamine producing an alkylating agent which reacted with cellular DNA giving rise to 7-methylguanine and O6-methylguanine. Alkylation of DNA was prevented by aminoacetonitrile and was proportional to the dimethylnitrosamine concentration over the range of 1--90 microM. Isolated hepatocytes were able to catalyze the removal of O6-methylguanine from their DNA. After formation of this product by reaction with N-methyl-N-nitrosourea or dimethylnitrosamine to give extents of alkylation in the range of 0.1--15.0 mumol O6-methylguanine per mole of guanine in DNA, the loss produced in 3 h incubation was comparable to that seen in vivo from liver DNA alkylated to the same extent. The isolated hepatocytes therefore, provide a useful system in which factors influencing O6-methylguanine persistence in DNA can be studied.
mesh_terms: D000478:Alkylation; D000818:Animals; D004247:DNA / Q000378:metabolism*; D004128:Dimethylnitrosamine / Q000378:metabolism*; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008770:Methylnitrosourea / Q000494:pharmacology; D051381:Rats
chemical_list: D006147:Guanine; C008450:7-methylguanine; D008770:Methylnitrosourea; D004247:DNA; C008449:O-(6)-methylguanine; D004128:Dimethylnitrosamine