Metabolism of nitrosomethyl-n-alkylamines in Fischer rats

To investigate a possible connection between the pattern of the excreted metabolites of a series of nitrosomethylalkylamines and their tumour spectrum in rats, the urinary metabolites of nitrosomethylalkylamines with alkyl chain lengths from C4 (n-butyl) to C14 (n-tetradecyl) have been studied, using male Fischer rats. All of these compounds induced a high incidence of tumours in the rats, but only those with chain lengths of 8, 10, 12 or 14 carbons induced bladder tumours. The principal metabolite from the nitrosamines with an odd number of carbons in the alkyl chain was nitrosomethyl-2-carboxyethylamine. Nitrososarcosine and nitrosomethyl-3-carboxypropylamine were the principal metabolites from those compounds with even-numbered chains. No trend was discernible between the pattern or yields of these acids and the carcinogenic effectiveness. The principal component in the neutral fractions was nitrosomethyl-2-oxopropylamine (less than or equal to 1% of the dose administered). Very small amounts were obtained from the odd-numbered chain compounds, but serially increasing amounts from the even-numbered chain compounds.