Binding of hydrogen sulfide by bismuth does not prevent dextran sulfate-induced colitis in rats

Several lines of evidence suggest that ulcerative colitis could be caused b y excessive bacterial production of H2S in the colon. A rodent model of col itis involves the feeding of nonabsorbable, carbohydrate-bound sulfate in t he form of dextran sulfate or carrageenan. The observation that metronidazo le blocks the development of this colitis suggested that the injurious agen t could be a sulfur-containing compound (such as H2S) that is released duri ng the bacterial metabolism of the nonabsorbed sulfate. We tested this poss ibility by feeding rats dextran sulfate, with or without bismuth subsalicyl ate, a compound that avidly binds H2S. Bismuth subsalicylate reduced the fe cal release of H2S in dextran sulfate-treated rats to values well below tha t of controls. Nevertheless, all the animals developed colitis. We conclude that excessive H2S production does not play a role in the dextran sulfate model of colitis.