Body nitrosation potential measured by a novel N-15 breath test

Oxygenated nitrogen species, for example, the protonated form of nitrous ac id (H2ONO+), dinitrogentrioxide (N2O3), dinitrogentetroxide (N2O4), or pero xynitrite (ONOO-), can react with amines to form molecular nitrogen. These reactions can occur spontaneously with primary aliphatic amines or via cyto chrome P450 catalysed reactions with secondary amines. in principle measure ments of the excretion of the molecular nitrogen generated by these reactio ns could be used as an index of the levels of oxygenated nitrogen compounds acting as nitrosating agents. To test this idea, [N-15(2)]urea (3 mmol) wa s administered orally to live patients infected with Helicobacter pylori (a s diagnosed by the [C-13]urea breath test) and to four healthy volunteers. All participants ingested 3-mmol sodium nitrate as a precursor for NA 5 min before the ingestion of the nitrogen tracer. During the test the participa nts breathed 100% oxygen to increase the sensitivity of detection of endoge nous molecular nitrogen. After the administration of [N-15(2)]urea, the pat ients with H. pylori showed significantly increased N-15 enrichments of exh aled N-2, expressed as delta value (parts per thousand), compared with heal thy volunteers (patients: 3.5 +/- 0.9 vs, volunteers: 1.3 +/- 0.4; p < .05) . We speculate that the endogenous production of molecular nitrogen is a pr otective process controlling the body NO and nitrite levels. The N-15 breat h technique allows the noninvasive estimation of the body nitrosation and c ould indicate the health risk, possibly the oxidative stress status, caused by highly reactive oxygenated nitrogen species and carbenium ion intermedi ates. (C) 1999 Elsevier Science inc.