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Titolo:
The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro
Autore:
Jaworek, J; Bilski, J; Jachimczak, B; Cieszkowski, M; Kot, M; Bielanski, W; Konturek, SJ;
Indirizzi:
Jagiellonian Univ, Univ Sch med, Chair Physiol, Krakow, Poland Jagiellonian Univ Krakow Poland Sch med, Chair Physiol, Krakow, Poland
Titolo Testata:
JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY
fascicolo: 2, volume: 51, anno: 2000,
pagine: 315 - 332
SICI:
0867-5910(200006)51:2<315:TEOAOP>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
HELICOBACTER-PYLORI INFECTION; DUODENAL-ULCER; SOMATOSTATIN; GASTRIN; UREASE; ACINI;
Keywords:
ammonia; pancreatic acini; pancreatic secretion; plasma gastrin; alkalization;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Jaworek, J Jagiellonian Univ, Univ Sch med, Chair Physiol, Ul Grzegorzecka16, Krakow, Poland Jagiellonian Univ Ul Grzegorzecka 16 Krakow Poland ow, Poland
Citazione:
J. Jaworek et al., "The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro", J PHYSL PH, 51(2), 2000, pp. 315-332

Abstract

Background: Recent studies clearly demonstrate that Helicobacter pylori (H. pylori) infection of the stomach causes persistent elevation of ammonia (NH3) in gastric juice leading to hypergastrinemia and enhanced pancreatic enzyme secretion. Methods: The aim of this study is to evaluate the influence of NH4OH on plasma gastrin level and exocrine pancreatic secretion in vivo in conscious dogs equipped with chronic pancreatic fistulas and on secretory activity of in vitro isolated acini obtained from the rat pancreas by collagenase digestion. The effects of NH4OH on amylase release from pancreatic acini were compared with those produced by simple alkalization of these acini with NaOH. Results: NH4OH given intraduodenally (i.d.) in increasing concentrations (0.5, 1.0, 2.0, 4.0, or 8.0 mM/L) resulted in an increase ofpancreatic protein output, reaching respectively 9%, 10%, 19%, 16% and 17%of caerulein maximum in these animals and in a marked increase in plasma gastrin level. NH4OH (8.0 mM/L, i.d.) given during intravenous (i.v.) infusion of secretin (50 pmol/kg-h) and cholecystokmin (50 pmol/kg-h) reduced theHCO3- and protein outputs by 35% and 37% respectively, as compared to control obtained with infusion of secretin plus cholecystokinin alone. When pancreatic secretion was stimulated by ordinary feeding the same amount of NH4OH administered i.d. decreased the HCO3- and protein responses by 78% and 47% respectively, and had no significant effect on postprandial plasma gastrin. In isolated pancreatic acini, increasing concentrations of NH4OH (10(-7)-10(-4) M) produced a concentration-dependent stimulation of amylase release, reaching about 43% of caerulein-induced maximum. When various concentrations of NH4OH were added to submaximal concentration of caerulein (10(-12)M) or urecholine (10(-5) M), the enzyme secretion was reduced at a dose 10(-5) M of NH4OH by 38% or 40%, respectively. Simple alkalization with NaOH of the incubation medium up to pH 8.5 markedly stimulated basal amylase secretion from isolated pancreatic acini, whereas the secretory response of these acini to pancreatic secretagogues was significantly diminished by about30%. LDH release into the incubation medium was not significantly changed in all tests indicating that NH4OH did not produce any apparent damage of pancreatic acini and this was confirmed by histological examination of theseacini. Conclusions: 1. NH4OH affects basal and stimulated pancreatic secretion. 2. The excessive release of gastrin may be responsible for the stimulation of basal pancreatic enzyme secretion in conscious animals, and 3. Theinhibitory effects of NH4OH on stimulated secretion might be mediated, at least in part, by its direct action on the isolated pancreatic acini possibly due to the alkalization of these acini.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/07/20 alle ore 14:29:31