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Characterization and Molecular Localization of Anion Transporters in Colonic Epithelial Cells
Author(s) -
RAJENDRAN VAZHAIKKURICHI M.,
BINDER HENRY J.
Publication year - 2000
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2000.tb05220.x
Subject(s) - butyrate , cotransporter , crypt , chemistry , epithelial polarity , secretion , apical membrane , symporter , microbiology and biotechnology , transporter , ion transporter , biochemistry , cell , biology , membrane , endocrinology , sodium , gene , organic chemistry , fermentation
A bstract : This study describes the identification and characterization of anion transporters in apical membrane (APM) and basolateral membrane (BLM) of rat distal colon. Cl‐HCO 3 , Cl‐OH, Cl‐butyrate, and butyrate‐HCO 3 exchanges and Na‐HCO 3 cotransporter are present in rat distal epithelial cells. Cl‐HCO 3 exchange (1) is present only in APM from surface, but not from crypt cells; (2) is also present in BLM; and (3) of surface cell is encoded by anion exchange (AE)‐1 isoform, whereas BLM Cl‐HCO 3 is encoded by AE2 isoform. Cl‐OH exchange is present only in APM, but not in BLM from surface and crypt cells, and is responsible for regulation of cell functions (i.e., cell pH and cell volume regulation). Butyrate‐HCO 3 exchange (1) is also present in apical membrane vesicles (AMV) from surface, but not from crypt cells; (2) is present in BLM; and (3) is responsible for SCFA‐dependent HCO 3 secretion. By contrast, Cl‐butyrate exchange: (1) is present in APM from both surface and crypt cells; (2) is not present in BLM; and (3) recycles butyrate by absorbing Cl. NaHCO 3 cotransport: (1) is present only in BLM; (2) is expressed predominantly in midcrypt regions; and (3) may be linked to HCO 3 secretion. A mechanism for HCO 3 movement across the crypt apical membrane has not as yet been identified.