Cl-HCO3 exchange and anion conductance in rat duodenal apical membrane vesicles.
Cl-HCO3 exchange and anion conductance in rat duodenal apical membrane vesicles.
复制标题
大鼠十二指肠顶膜囊泡中的 Cl-HCO3 交换和阴离子电导。
DOI：
10.1152/ajpgi.1989.257.4.g661
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
L. Turnberg
中科院分区：
文献类型：
--
作者：
C. Brown;C. Dunk;L. Turnberg
Transport mechanisms for Cl and HCO3 anions in the apical membrane of rat duodenal enterocytes have been characterized using brush-border membrane vesicles. 36Cl uptake was stimulated by outwardly directed gradients of OH, HCO3, and Cl anions. The anion exchanger was sensitive to inhibition by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) (Ki, 1.3 mmol/l), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and furosemide. The process was electroneutral, since voltage clamping the membrane potential to 0 mV or applying a large inside-positive potential had no effect on the magnitude of uptake. The kinetic properties of the exchanger were measured and an apparent Km of 9.8 mM Cl and a Vmax of 134 nmol.mg protein-1.4 s-1 were found. In addition, an electrogenic conductive component of 36Cl uptake was found. This component was dependent on an inside-positive membrane potential and was inhibited by the Cl channel blocker diphenylamine-2-carboxylate. SITS, DIDS, and furosemide had no effect on the electrogenic component of 36Cl uptake. An apparent anion selectivity of SCN greater than I greater than Br greater than Cl greater than HCO3 greater than SO4 greater than Glu greater than PO4 was found. These results support the presence of both Cl-HCO3 exchange and a conductive anion channel in the apical membrane of rat duodenal enterocytes.
