Document Detail

Enhanced H+ diffusion by NH4+/HCO3-: implications for Helicobacter-pylori-associated peptic ulceration.
MedLine Citation:
PMID:  8513985     Owner:  NLM     Status:  MEDLINE    
The in vitro effect of ammonium bicarbonate buffer on mucus H+ permeability is reported here. The diffusional resistance of mucus and water was demonstrated to be dependent on buffer concentration, and the contrast between the two types of layers was most pronounced for low buffer concentration near neutrality. Moreover, the pKa values of HCO3- and NH3 had a profound effect on measured DHCl. These in vitro studies suggest that a potentially damaging high local concentration of NH3 and HCO3- within the mucus layer generated by the action of Helicobacter pylori urease on endogenous intragastric urea could greatly accelerate proton flux to the surface epithelium by operation of a buffer shuttle. This results in enhanced H+ permeability, particularly at pKa values of HCO3- and NH3, and that in extreme circumstances this may result in gastric ulcer formation.
M A Desai; P M Vadgama
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Digestion     Volume:  54     ISSN:  0012-2823     ISO Abbreviation:  Digestion     Publication Date:  1993  
Date Detail:
Created Date:  1993-07-22     Completed Date:  1993-07-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0150472     Medline TA:  Digestion     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  32-9     Citation Subset:  IM    
Department of Medicine (Clinical Biochemistry), University of Manchester, Hope Hospital, Salford, UK.
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MeSH Terms
Bicarbonates / pharmacology*
Gastric Mucosa / drug effects*,  metabolism
Helicobacter Infections / complications*
Helicobacter pylori / enzymology*
Hydrogen-Ion Concentration
Mucus / drug effects*
Stomach Ulcer / microbiology*
Urease / metabolism*
Reg. No./Substance:
0/Bicarbonates; 1066-33-7/ammonium bicarbonate; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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