Abstract: AIM: Explore the relationshipbetween the protection of CBS on gastric mucosa and the effect of CBS on gastric mucosal NO content and NOS activity.METHODS: The mucosal injury was induced by ethanol n rat and then treated with CBS.NO content and NOS activity were determined by benzidine-fluorescence spectrophotometer.RESULTS: CBS was applied intragastricly, which significantly reduced the area of gastric ulcer and inhibit iNOS activity.As a result, the NO level was reduced to normal.When CBS was applied intraperitoneally,the NO level of gastric mucosa as well as iNOS activity was reduced, and cNOS activity was increased.In Vitro experiment showed that CBS inhibited NOS activity significantly.CONCLUSION: CBS inhibits the increased iNOS activity and NO level, which may be an underlying biochemical mechanism for its protective on gastric mucosa.

Key words: colloidal bismuth subcitrate, NO, iNOS, cNOS, gastric ulcer