N-nitrosoproline excretion in patients with gastric lesions and in a control population.

N-Nitrosoproline (NPRO) excretion was measured in a group of hospital in-patients who were identified as either bearing gastric lesions or having apparently healthy stomachs. NPRO was assayed in background 24-h urine samples and then in urines collected after loading doses of nitrate and proline. The presence of gastric lesions was associated with altered gastric juice pH and nitrite concentration, but not with NPRO excretion. The significance of NPRO excretion as a marker of endogenous nitrosation is dependent on the interpretation of this result.