Significance of ammonia produced by Helicobacter pylori

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Abstract
Objective To clarify the effect of ammonia produced by Helicobacter pylori, which has strong urease activity, on the blood ammonia level. Design (1) The quantification of ammonia production by live H. pylori in vitro. (2) The measurement of venous and portal ammonia levels following the instillation of H. pylori into the stomachs of normal or cirrhotic rats. Methods (1) The urease reaction was carried out at 37C with bacteria suspended in phosphate-buffered saline and 400 mmol/l urea solution in acetate buffer, pH 5.0. (2) Bacterial suspensions with or without urea solution were instilled into the stomachs of male normal Wistar rats or into rats in which cirrhosis had been induced by injection of carbon tetrachloride; venous and portal ammonia levels were then measured. Results (1) Ammonia production by 105 CFU/ml of live H. pylori was about 5.88–11.76 mmol/l (0.01–0.02%) at 37C over 120 min. (2) In the normal rats, when 107CFU/ml of H. pylori was instilled into the stomach, the venous ammonia level reached about 120 xmol/l after 120min, and about 210 mUmol/l in the cirrhotic rats. Conclusions These data suggest that the ammonia produced by H. pylori may play a role in the pathogenesis of hyperammonemia if this organism is widely distributed and is present in large numbers in the stomach, particularly in the presence of hepatic cirrhosis.

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