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Titolo:
IRRITANT AND PROTECTIVE ACTION OF UREA UREASE AMMONIA IN RAT GASTRIC-MUCOSA - DIFFERENT EFFECTS OF AMMONIA AND AMMONIUM ION
Autore:
TAKEUCHI K; OHUCHI T; HARADA H; OKABE S;
Indirizzi:
KYOTO PHARMACEUT UNIV,DEPT APPL PHARMACOL KYOTO 607 JAPAN
Titolo Testata:
Digestive diseases and sciences
fascicolo: 2, volume: 40, anno: 1995,
pagine: 274 - 281
SICI:
0163-2116(1995)40:2<274:IAPAOU>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
ENDOGENOUS PROSTAGLANDINS; CAMPYLOBACTER-PYLORI; HELICOBACTER-PYLORI; ALKALINE RESPONSE; HYPERTONIC NACL; MILD IRRITANTS; STOMACH; CYTOPROTECTION; NECROSIS; INJURY;
Keywords:
UREA UREASE; AMMONIA; NH4OH; NH4CL; IRRITATION PROTECTION; RAT STOMACH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
K. Takeuchi et al., "IRRITANT AND PROTECTIVE ACTION OF UREA UREASE AMMONIA IN RAT GASTRIC-MUCOSA - DIFFERENT EFFECTS OF AMMONIA AND AMMONIUM ION", Digestive diseases and sciences, 40(2), 1995, pp. 274-281

Abstract

The effects of urea-urease-ammonia on the rat gastric mucosa were examined and compared with those of NH4OH and NH4Cl. The mucosal application of urea with urease produced a reduction in potential difference (PD) in a dose-related manner for urea, and a significant drop was observed by >0.1% urea in the presence of 100 units urease. Such PD reduction was also observed when the mucosa was exposed to either NH4OH (>0.03%) or NH4Cl (>1%); Delta PD (20 mV) caused by 0.3% NH4OH and 3% NH4Cl was equivalent to that induced by 0.5% urea + urease (100 units). The combined oral administration of urea (similar to 6%) and urease (100units) did not induce any macroscopic damage in the gastric mucosa. NH4Cl given orally had no or little effect on the mucosa at any dose levels even at 10%, while NH4OH given orally caused hemorrhagic lesions in the mucosa at the dose of >0.3%. In contrast, both urea + urease and NH4Cl given prior to HCl/ethanol protected the gastric mucosa against damage in a dose-related manner, and a significant effect was obtained by urea at >0.5% and by NH4Cl at >1%. NH4OH was also effective in reducing the severity of HCl/ethanol-induced gastric lesions at lower dose (0.3%). The protective effect of urea + urease was attenuated significantly by prior administration of indomethacin or coadministration of hydroxyurea, while that of NH4Cl or NH4OH was mitigated by indomethacin. These results suggest that the urea-urease-ammonia system in thestomach may be beneficial in normal conditions; ammonia produced by the hydrolysis of urea yields NH4OH and NH4Cl in the lumen, both of which act on the stomach as mild irritant, resulting in adaptive cytoprotection mediated by endogeneous prostaglandins.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 04:20:09