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NBCn1 ( Slc4a7 ) is a major HCO 3 − importer in murine duodenum and essential for basal and stimulated HCO 3 − secretion in vivo
Author(s) -
Chen Mingmin,
Praetorius Jeppe,
Wang Jian,
Stieger Nicole,
Zheng Wen,
Riederer Brigitte,
Krabbenhöft Anja,
Bonhagen Janina,
Rausch Brigitte,
Engelhardt Regina,
Dringenberg Ulrike,
Aalkjaer Christian,
Seidler Ursula
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.799.4
Subject(s) - duodenum , bicarbonate , cotransporter , chemistry , secretion , in vivo , sodium–hydrogen antiporter , acid–base homeostasis , medicine , endocrinology , biochemistry , biology , sodium , microbiology and biotechnology , organic chemistry
HCO 3 − secretion protects the proximal duodenum against damage by gastric acid. The molecular details of basolateral HCO 3 − import are unknown, but several base importers are expressed in the basolateral membrane of duodenocytes. The electroneutral sodium bicarbonate cotransporter NBCn1 ( Slc4a7 ) is expressed in the villous region of the duodenum. To elucidate its importance for duodenal bicarbonate secretion, as well as pH i regulation, we measured basal and stimulated HCO 3 − secretion in the proximal duodenum of anesthetized Slc4a7 ‐/‐ mice and wt littermates in vivo during controlled systemic acid/base parameters, by continuous determination of the HCO 3 − that was secreted into the luminal perfusate, and in isolated duodenal mucosa in vitro in Ussing‐chambers by pH‐stat titration. In addition, we fluorometrically assessed base‐uptake rates after acidification of intact villi and isolated duodenocytes. Slc4a7 ‐/‐mice displayed significantly lower basal and forskolin‐stimulated duodenal HCO 3 − secretion in vivo than wt littermates. This difference was markedly larger in vivo than in isolated mucosa. The Na + ‐ and HCO 3 − ‐dependent base uptake rate was significantly decreased in Slc4a7 ‐/‐ (33.2%) compared to wt villus duodenocytes. The electroneutral Na + HCO 3 − cotransporter Slc4a7 is a major HCO 3 − importer in murine duodenum and is essential for basal and stimulated HCO 3 − secretion in vivo .