Effects of cytotoxic factors of Helicobacter pylori on superoxide generation in situ in the rabbit stomach.

OBJECTIVE: To evaluate the effect of certain cytotoxic products of Helicobacter pylori on superoxide generation in situ and on the infiltration by polymorphonuclear cells into the gastric mucosa. The agents studied were ammonia, a culture supernatant of H. pylori, and N-formyl-methionyl-leucyl-phenylalanine (FMLP), a chemotactic factor. METHODS: One or two of these agents were dripped onto rabbit gastric epithelium. The number of polymorphonuclear cells in gastric mucosa were counted histologically. Superoxide generation was measured by a chemiluminescence method, using a Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one , a chemiluminescence probe that responds to the generation of superoxides and singlet oxygen radicals. Bovine erythrocyte copper zinc superoxide dismutase was dripped to confirm that the increase in photon counts was a direct consequence of the generation of superoxides. RESULTS: The greatest infiltration of polymorphonuclear cells into the gastric mucosa was observed with the administration of 1 mmol/l FMLP followed by 5.9 mmol/l ammonia, and 10 mmol/l FMLP followed by 59 mmol/l ammonia. There was no increase in the number of polymorphonuclear cells in the other experiments. Increased chemiluminescence was observed in conjunction with the infiltration of polymorphonuclear cells and was inhibited by superoxide dismutase. CONCLUSIONS: Acute gastritis and superoxide generation in situ were induced by ammonia after pretreatment with FMLP.