Metabolism and cellular interactions of N-nitrosodiethanolamine

N-Nitrosodiethanolamine (NDELA) labelled with 14C at the alpha carbon was administered by gavage to adult male Fischer 344 rats at various doses ranging from 0.6 to 100 mg per rat. The proportion of the dose excreted as 14CO2 was small, ranging from 0.27% at the lowest dose to 0.83% at the highest in 24 h. At all doses, approximately 95% of the dose of radioactivity (most of which was NDELA) appeared in the urine within 24 h, but the proportion of metabolites increased from 7% to 14% from the lowest to the highest dose. The specific activity of the nucleic acids isolated from the liver of rats given 100 mg and 100 microCi of NDELA was very low and was the same at 6 h and 24 h after treatment (70 dpm/mg DNA, 92-95 dpm/mg RNA). N7-(2-Hydroxyethyl)guanine and O6-(2-hydroxyethyl)-guanine were tentatively identified in the hydrolysates of the nucleic acids, comprising 10% and 4%, respectively, of the DNA radioactivity; there was no difference between the amounts found 6 h and 24 h after NDELA treatment. In addition to NDELA, four components were separated from rat urine, and two were identified. One is the glucuronide of NDELA, the other is N-nitroso-N-(2-hydroxyethyl)carboxymethylamine. Neither nitroso-2-hydroxymorpholine nor a sulfate of NDELA was detected.