Functional coupling of apical Cl-/HCO3- exchange with CFTR in stimulated HCO3- secretion by guinea pig interlobular pancreatic duct.
Functional coupling of apical Cl-/HCO3- exchange with CFTR in stimulated HCO3- secretion by guinea pig interlobular pancreatic duct.
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DOI：
10.1152/ajpgi.90697.2008
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发表时间：
2009-04
期刊：
影响因子：
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通讯作者：
A. K. Stewart;A. Yamamoto;M. Nakakuki;T. Kondo;S. Alper;H. Ishiguro
中科院分区：
文献类型：
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作者：
A. K. Stewart;A. Yamamoto;M. Nakakuki;T. Kondo;S. Alper;H. Ishiguro
胰腺导管上皮细胞产生富含HCO(3)(-)的液体。HCO(3)(-)跨导管顶膜的转运被认为是由SLC26介导的Cl(-)/HCO(3)(-)交换和CFTR介导的HCO(3)(-)电导共同调节的，其比例贡献部分取决于基因表达和管腔阴离子组成的轴向变化。本研究观察了豚鼠胰腺小叶间导管顶端Cl(-)/HCO(3)(-)交换的特点及其与CFTR活性的功能相互作用。在HCO3)(-)-CO(2)存在的情况下，用醋酸盐预脉冲或鲁米诺氯(-)去除来碱化装有BCECF的发光微灌流管上皮细胞。鲁米那二氢二氢化合物(H(2)DIDS)可显著抑制cAMP刺激的导管内氯离子恢复(名义上的氯离子/HCO(3)(-)交换)后的细胞内pH恢复，而鲁米那二氢二氢化合物(H(2)DIDS)可显著抑制细胞内pH的恢复，并被鲁米那CFTR抑制剂INH-172(CFTRinh-172)加速，且对升高的BASH K(+)浓度不敏感。根据管腔pH值和体积的变化，在无HCO(3)(-)、富氯(-)的溶液中，将CFTRinh-172引入含有BCECF-葡聚糖的密封管腔可增强cAMP刺激的HCO(3)(-)分泌。在短暂的小去极化后，流明除氯(-)产生了持续的约15 mV的细胞超极化，与电生氯(-)/HCO(3)(-)交换相一致。H(2)DIDS抑制超极化，CFTRinh-172增强超极化。RT-PCR检测小叶间导管表达编码CFTR、SLc26a6和SLc26a3的mRNAs。因此，依赖于氯的胰管顶端HCO(3)(-)的分泌主要是由类SLc26a6的Cl(-)/HCO(3)(-)交换器介导的，并被CFTR抑制而加速。本研究证实了豚鼠胰腺小叶间管顶膜上CFTR与类SLc26a6的Cl(-)/HCO(3)(-)交换活性的功能偶联。
Pancreatic ductal epithelium produces a HCO(3)(-)-rich fluid. HCO(3)(-) transport across ductal apical membranes has been proposed to be mediated by both SLC26-mediated Cl(-)/HCO(3)(-) exchange and CFTR-mediated HCO(3)(-) conductance, with proportional contributions determined in part by axial changes in gene expression and luminal anion composition. In this study we investigated the characteristics of apical Cl(-)/HCO(3)(-) exchange and its functional interaction with Cftr activity in isolated interlobular ducts of guinea pig pancreas. BCECF-loaded epithelial cells of luminally microperfused ducts were alkalinized by acetate prepulse or by luminal Cl(-) removal in the presence of HCO(3)(-)-CO(2). Intracellular pH recovery upon luminal Cl(-) restoration (nominal Cl(-)/HCO(3)(-) exchange) in cAMP-stimulated ducts was largely inhibited by luminal dihydro-DIDS (H(2)DIDS), accelerated by luminal CFTR inhibitor inh-172 (CFTRinh-172), and was insensitive to elevated bath K(+) concentration. Luminal introduction of CFTRinh-172 into sealed duct lumens containing BCECF-dextran in HCO(3)(-)-free, Cl(-)-rich solution enhanced cAMP-stimulated HCO(3)(-) secretion, as calculated from changes in luminal pH and volume. Luminal Cl(-) removal produced, after a transient small depolarization, sustained cell hyperpolarization of approximately 15 mV consistent with electrogenic Cl(-)/HCO(3)(-) exchange. The hyperpolarization was inhibited by H(2)DIDS and potentiated by CFTRinh-172. Interlobular ducts expressed mRNAs encoding CFTR, Slc26a6, and Slc26a3, as detected by RT-PCR. Thus Cl(-)-dependent apical HCO(3)(-) secretion in pancreatic duct is mediated predominantly by an Slc26a6-like Cl(-)/HCO(3)(-) exchanger and is accelerated by inhibition of CFTR. This study demonstrates functional coupling between Cftr and Slc26a6-like Cl(-)/HCO(3)(-) exchange activity in apical membrane of guinea pig pancreatic interlobular duct.