Helicobacter pylori infection reduces intraluminal nitric oxide in humans

It has recently been demonstrated that nitric oxide (NO) is highly concentrated in the gastric lumen and plays an important role in defending against pathogenic microorganisms in the stomach. NO in the gastric lumen is mainly delivered by extrinsic sources from saliva. We studied whether Helicobacter pylori infection affected intraluminal NO levels in humans. H. pylori infection was diagnosed on the basis of histology and culture or (13C)-urea breath test. Air and gastric juice in the gastric lumen were collected endoscopically. The concentration of intraluminal NO was measured by a chemiluminescence system, using an NO analyzer. The concentration of nitrite in gastric juice was measured by the Griess reaction. The intraluminal concentration of NO in H. pylori-positive patients (198.2 ± 41 parts per billion [ppb] mean ± SE; n = 70) was significantly lower than that in H. pylori-negative patients (353.0 ± 57.9 ppb; n = 43; P < 0.05). In contrast, the concentration of nitrite in gastric juice in H. pylori-positive patients (57.7 ± 12.3 μM; n = 70) was significantly higher than that in H. pylori-negative patients (25.9 ± 6.4 μM; n = 43, P < 0.01). The intraluminal concentration of NO in H. pylori-positive patients was markedly increased and the concentration of nitrite in H. pylori-positive patients was markedly decreased following the completion of eradication therapy. Based on these results, we propose that a decrease in NO and excess nitrite production in the gastric lumen are associated with H. pylori infection and may play an important role in the pathogenesis of H. pylori-related abnormalities.