title: Gastric ammonia has a potent ulcerogenic action on the rat stomach.
abstract: BACKGROUND
  The pathophysiological mechanism by which Helicobacter pylori induces mucosal injury has not been clarified. The aim of this study was to investigate the role of urea, urease, and ammonia in rat gastric mucosal lesions using an ex vivo chamber model.
  
  
  METHODS
  Two groups of rats, normotensive rats and those subjected to ischemia, were studied. The gastric mucosa was examined histologically and macroscopically, and the transmucosal potential difference was measured.
  
  
  RESULTS
  Instillation of urea into the stomach generated ammonia in the presence of urease. The amount of ammonia was increased depending on the concentration of urea and was closely associated with the severity of the histological lesions. The exposure of the stomach to 15-60 mmol/L ammonium hydroxide induced both a reduction in transmucosal potential difference and microscopic damage to the gastric mucosa in normotensive rats. Moreover, 15-60 mmol/L ammonium hydroxide produced severe macroscopic gastric lesions in the rats subjected to ischemia.
  
  
  CONCLUSIONS
  These results show that ammonia is deleterious to the gastric mucosa and suggest the importance of urea, urease, and ammonia in the pathophysiology of gastric diseases in H. pylori-infected patients.
authors.affiliation: Department of Geriatric Medicine, Faculty of Medicine, Kyoto University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Murakami
authors.forename: H
authors.initials: H
authors.lastname: Saita
authors.forename: S
authors.initials: S
authors.lastname: Teramura
authors.forename: H
authors.initials: H
authors.lastname: Dekigai
authors.forename: K
authors.initials: K
authors.lastname: Asagoe
authors.forename: S
authors.initials: S
authors.lastname: Kusaka
authors.forename: T
authors.initials: T
authors.lastname: Kita
mesh_terms: D000200:Action Potentials; D000641:Ammonia / Q000633:toxicity*; D000818:Animals; D005753:Gastric Mucosa / Q000378:metabolism / Q000473:pathology; D016480:Helicobacter pylori / Q000201:enzymology / Q000472:pathogenicity; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013276:Stomach Ulcer / Q000139:chemically induced*; D014508:Urea / Q000378:metabolism; D014510:Urease / Q000633:toxicity
chemical_list: D000641:Ammonia; D014508:Urea; D014510:Urease