Intragastric nitric oxide/nitrite in Helicobacter pylori-infected subjects

Fandriks L, von Bothmer C, Aneman A, Olbe L, Pettersson A. Intragastric nitric oxide/nitrite in Helicobacter pylori-infected subjects. Background: Nitrite (NO 2 ) in swallowed saliva is reduced to nitric oxide (NO) and other nitrogen oxides by the intragastric acidity. This mechanism is probably important for the intragastric clearance of ingested micro-organisms and nitrosating compounds. The study examines the balance between intragastric NO and NO 2 in relation to endogenous acid production and infection 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 chemiluminescence technique and pH as well as NO 2 were analysed in gastric aspirates. Results: Gastric NO was slightly lower in H. pylori-positive subjects (1560 ± 21 [ ppb) than in uninfected controls (2112 ± 430 ppb; P > 0.05) during basal conditions, whereas both pH and NO 2 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 NO 2 - concentration in gastric aspirates were significantly higher in H. pylori positives than in the controls. Furthermore, during omeprazole treatment the intragastric NO levels were almost absent in H. pylori positives, whereas approximately 50% remained in H. pylori-negative individuals. Conclusion: Proton-pump inhibition in H. pylori-infected individuals abolishes the intragastric chemical reduction of swallowed NO 2 - in the fasting stomach.