Intragastric nitric oxide/nitrite in Helicobacter pylori-infected subjects

Background: Nitrite (NO2-) in swallowed saliva is reduced to nitric oxide ( NO) and other nitrogen oxides by the intragastric acidity. This mechanism i s probably important for the intragastric clearance of ingested micro-organ isms and nitrosating compounds. The study examines the balance between intr agastric NO and NO2- in relation to endogenous acid production and infectio n with Helicobacter pylori. Methods: Six healthy H. pylori-negative and six H. pylori-positive volunteers with no known gastroduodenal pathology were examined after an overnight fast. Gastric NO was measured using a chemilumi nescence technique and pH as well as NO2- were analysed in gastric aspirate s. Results: Gastric NO was slightly lower in H. pylori-positive subjects (1 560 +/- 211 ppb) than in uninfected controls (2112 +/- 430 ppb; P > 0.05) d uring basal conditions, whereas both pH and NO2- concentration were similar in the two groups. During inhibition of acid secretion (omeprazole 20 mg b .i.d. over 5 days) median pH and mean NO2- concentration in gastric aspirat es were significantly higher in H. pylori positives than in the controls. F urthermore, during omeprazole treatment the intragastric NO levels were alm ost absent in H. pylori positives, whereas approximately 50% remained in H. pylori-negative individuals. Conclusion: Proton-pump inhibition in H. pylo ri-infected individuals abolishes the intragastric chemical reduction of sw allowed NO2- in the fasting stomach.