Effect of administration of the carcinogen dimethylnitrosamine on urinary 7-methylguanine.
1. Evidence is presented for the excretion of 7-methylguanine in normal rat urine at a rate of approx. 65mug./day. Experiments with animals in which the nucleic acids had been prelabelled by treatment of the neonatal rats with [(14)C]-formate gave evidence that the methylated base originated in the nucleic acids of the rat. 2. Injection of [(14)C]dimethylnitrosamine leads to an increased excretion of 7-methylguanine, and the base becomes labelled in the methyl group. The disappearance of labelled 7-methylguanine formed in nucleic acids of rats treated with the carcinogen therefore does not take place by an N-demethylation reaction, but by liberation of the intact methylated base.
D000478:Alkylation; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D002247:Carbon Isotopes; D002273:Carcinogens / Q000494:pharmacology*; D002852:Chromatography, Ion Exchange; D002854:Chromatography, Paper; D005561:Formates / Q000378:metabolism; D006147:Guanine / Q000652:urine*; D009602:Nitrosamines / Q000494:pharmacology*; D009696:Nucleic Acids / Q000378:metabolism; D051381:Rats
D002247:Carbon Isotopes; D002273:Carcinogens; D005561:Formates; D009602:Nitrosamines; D009696:Nucleic Acids; D006147:Guanine