Urinary excretion of nitrosodimethylamine and nitrosoproline in humans: interindividual and intraindividual differences and the effect of administered ascorbic acid and alpha-tocopherol.

Gas chromatography-high resolution mass spectrometry methods were developed for quantifying nitrosodimethylamine (NDMA) and nitrosoproline (NPRO) in human urine. The limits of quantitation of these methods, which utilize stable isotope analogues of NDMA and NPRO as internal standards, were 5 pg per ml for NDMA and 0.14 ng per ml for NPRO.

Inhibitory effect of alpha-tocopherol on the formation of nitrosomorpholine in mice treated with morpholine and exposed to nitrogen dioxide.

The possibility that alpha-tocopherol (vitamin E) inhibits the formation of nitrosomorpholine (NMOR) in vivo was investigated in mice orally pretreated with alpha-tocopherol (2.5-100 mg/kg body wt) once daily for 6 days. Twenty-four hours later, the animals were injected i.

Studies on the antimutagenic activity of ascorbic acid in vitro and in vivo.

The possibility that ascorbic acid, as a nucleophile, may inhibit mutagenicity induced by electrophilic metabolites of N-nitroso compounds was examined. In vitro data are presented to show that ascorbic acid does not decrease the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in a modified Ames bacterial mutagenicity system if deionized water is used to prepare the incubation medium. However, ascorbic acid prevents the mutagenicity of MNNG in vitro if added to bacteria in a medium prepared with either sterile tap water or deionized water and Cu2+ ions and that this antimutagenic response is blocked by EDTA.

Formation of N-nitrosomorpholine in mice treated with morpholine and exposed to nitrogen dioxide.

The possibility of N-nitrosomorpholine formation was investigated in mice treated with morpholine and then exposed to 45 p.p.m.