title: Hyperammonemia reduces water immersion--restraint stress gastric ulcers in rats.
abstract: 1. The influence of hyperammonemia (produced by the continuous intraperitoneal infusion of ammonium acetate for 6 days) on stress-induced gastric ulcer formation was investigated in conscious rats. 2. Continuous ammonium acetate infusion significantly reduced stress-induced gastric ulceration concomitant with an increase in gastric blood flow, as determined using radioactive microspheres. The serum levels of L-arginine as well as nitrite and nitrate (oxidative byproducts of nitric oxide) were increased by ammonium acetate infusion. 3. Prior administration of N omega-nitro-L-arginine methyl ester, a competitive nitric oxide synthase inhibitor, substantially attenuated the increase in gastric blood flow caused by ammonium acetate infusion and diminished the protective effect on gastric ulceration. 4. These findings suggest that the synthesis of endogenous nitric oxide from L-arginine is accelerated by continuous ammonium acetate infusion when the urea cycle remains intact and has a substantial cytoprotective effect on the stomach, probably through maintaining the gastric mucosal microcirculation.
authors.affiliation: Department of Emergency and Critical Care Medicine, Kansai Medical University, Osaka, Japan. ken-yu@mb.aikis.or.jp
authors.forename: T
authors.initials: T
authors.lastname: Ishihara
authors.forename: T
authors.initials: T
authors.lastname: Takada
authors.forename: Y
authors.initials: Y
authors.lastname: Shoji
authors.forename: Y
authors.initials: Y
authors.lastname: Uedono
authors.forename: N
authors.initials: N
authors.lastname: Takeyama
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000085:Acetates / Q000097:blood / Q000627:therapeutic use*; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009573:Nitrites / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects; D012149:Restraint, Physical; D013276:Stomach Ulcer / Q000097:blood / Q000188:drug therapy* / Q000523:psychology; D013312:Stress, Physiological / Q000188:drug therapy*; D014867:Water
chemical_list: D000085:Acetates; D004791:Enzyme Inhibitors; D009566:Nitrates; D009573:Nitrites; D014867:Water; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; C018824:ammonium acetate; D019331:NG-Nitroarginine Methyl Ester