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- Title
Review article: duodenal bicarbonate – mucosal protection, luminal chemosensing and acid–base balance.
- Authors
KAUNITZ, J. D.; AKIBA, Y.
- Abstract
The duodenum serves as a buffer zone between the stomach and the jejunum. Over a length of only 25 cm, large volumes of strong acid secreted by the stomach must be converted to the neutral–alkaline chyme of the hindgut lumen, generating large volumes of CO2. The duodenal mucosa consists of epithelial cells connected by low-resistance tight junctions, forming a leaky epithelial barrier. Despite this permeability, the epithelial cells, under intense stress from luminal mineral acid and highly elevated Pco2, maintain normal functioning. Bicarbonate ion uniquely protects the duodenal epithelial cells from acid-related injury. The specific protective mechanisms likely involve luminal bicarbonate secretion, intracellular pH buffering and interstitial buffering. Furthermore, the duodenum plays an active role in foregut acid–base homeostasis, absorbing large amounts of H+ and CO2. We have studied mucosal protection and acid–base balance using live-animal fluorescence ratio microimaging and by performing H+ and CO2 balance studies on duodenal perfusates. On the basis of these data, we have formulated novel hypotheses with regard to mucosal protection.
- Subjects
DUODENUM; JEJUNUM; SMALL intestine; MUCOUS membranes; CARBONIC acid; BIOLOGICAL transport; HYDROGEN-ion concentration; BICARBONATE ions
- Publication
Alimentary Pharmacology & Therapeutics, 2006, p169
- ISSN
0269-2813
- Publication type
Article
- DOI
10.1111/j.1365-2036.2006.00041.x