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Slc26a3(Down‐regulated in adenoma) Cl/HCO 3 exchanger is responsible for Cl absorption and HCO 3 secretion in the murine large intestine
Author(s) -
Suzuki Yuichi,
Kawamata Koichi,
Schweinfest CW,
Soleimani M,
Hayashi Hisayoshi
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.796.20
Subject(s) - ussing chamber , cecum , chemistry , absorption (acoustics) , secretion , large intestine , biophysics , medicine , microbiology and biotechnology , endocrinology , biochemistry , biology , materials science , composite material
In the large intestine a Cl/HCO 3 exchanger is suggested to be involved in Cl absorption which is closely associated with Na absorption mediated by Na/H exchanger. A Cl/HCO 3 exchanger is also responsible for HCO 3 secretion. Molecular identity of these Cl/HCO 3 exchanger(s) was investigated using mice with gene‐targeted knockout (KO) of Cl/HCO 3 exchangers: Slc26a3, down‐regulated in adenoma (Dra). Isolated cecum and distal colon were mounted in Ussing chambers. We measured transepithelial fluxes of 22 Na and 36 Cl, and by using a pH‐stat device a luminal alkalinization rate. Essentially similar findings were obtained for both the cecum and distal colon. In control (ddy strain) and wild type mice, mucosa‐to‐serosa flux (J ms ) was larger than serosa‐to‐mucosa flux (J sm ) for both 22 Na and 36 Cl. In contrast, in DraKO mice J ms and J sm for 36 Cl were both markedly reduced and net 36 Cl absorption was almost, if not entirely, abolished, while J ms and J sm for 22 Na were not noticeably affected. Cl‐dependent HCO 3 secretion was completely abolished in DraKO mice. These results suggest that, under Ussing chamber condition, Dra is a major transporter responsible for both the absorptive and secretory transport of Cl, and for most of the net Cl absorption. Dra is also involved in Cl‐dependent HCO 3 secretion.