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 Hel icobacter pylori on superoxide generation in situ and on the infiltrat ion by polymorphonuclear cells into the gastric mucosa. The agents stu died were ammonia, a culture supernatant of H. pylori, and N-formyl-me thionyl-leucyl-phenylalanine (FMLP), a chemotactic factor. Methods: On e or two of these agents were dripped onto rabbit gastric epithelium. The number of polymorphonuclear cells in gastric mucosa were counted h istologically. Superoxide generation was measured by a chemiluminescen ce method, using a Cypridina luciferin analog, phenyl-3,7-dihydroimida zo[1,2-alpha]pyrazin-3-one, a chemiluminescence probe that responds to the generation of superoxides and singlet oxygen radicals. Bovine ery throcyte copper zinc superoxide dismutase was dripped to confirm that the increase in photon counts was a direct consequence of the generati on of superoxides. Results: The greatest infiltration of polymorphonuc lear cells into the gastric mucosa was observed with the administratio n 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 chemilumin escence was observed in conjunction with the infiltration of polymorph onuclear cells and was inhibited by superoxide dismutase. Conclusions: Acute gastritis and superoxide generation in situ were induced by amm onia after pretreatment with FMLP.