Rubera I, Tauc M, Bidet M, Poujeol C, Cuiller B, Watrin A, Touret N, Poujeol P
Unité Mixte de Recherche, Centre National de la Recherche Scientifique 6548, Université de Nice-Sophia Antipolis, O6108 Nice Cedex 2, France.
Am J Physiol. 1998 Nov;275(5):F651-63. doi: 10.1152/ajprenal.1998.275.5.F651.
Cl- conductances were studied in cultured rabbit proximal convoluted tubule (PCT) epithelial cells and compared with those measured in cultured distal bright convoluted tubule (DCTb) epithelial cells. Using the whole cell patch-clamp technique, three types of Cl- conductances were identified in DCTb cultured cells. These consisted of volume-sensitive, Ca2+-activated, and forskolin-activated Cl- currents. In PCT cultured cells, only volume-sensitive and Ca2+-activated Cl- currents were recorded. The characteristics of Ca2+-activated currents in PCT cells closely resembled those in DCTb cells. Volume-sensitive Cl- currents could be elicited both in PCT and in DCTb cells by hypotonic stress. The pharmacological profile of this conductance was established for both cell types. Forskolin activated a linear Cl- current in DCTb cells but not in PCT cells. This conductance was insensitive to DIDS and corresponds to cystic fibrosis transmembrane conductance regulator (CFTR)-like channels. Quantitative measurements of SPQ fluorescence showed that only the apical membrane of DCTb cells possessed a Cl- pathway that was sensitive to forskolin. RT-PCR experiments showed the presence of CFTR mRNA in both cultures, whereas immunostaining experiments revealed the expression of CFTR in DCTb cells only. The physiological role of the different types of channels is discussed.
对培养的兔近端曲小管（PCT）上皮细胞的氯离子电导进行了研究，并与培养的远端明亮曲小管（DCTb）上皮细胞中测得的氯离子电导进行了比较。使用全细胞膜片钳技术，在培养的DCTb细胞中鉴定出三种类型的氯离子电导。它们包括容积敏感性、钙激活和福斯高林激活的氯离子电流。在培养的PCT细胞中，仅记录到容积敏感性和钙激活的氯离子电流。PCT细胞中钙激活电流的特性与DCTb细胞中的非常相似。低渗应激可在PCT和DCTb细胞中引发容积敏感性氯离子电流。已确定了这两种细胞类型中这种电导的药理学特征。福斯高林在DCTb细胞中激活了线性氯离子电流，但在PCT细胞中未激活。这种电导对二乙氨基二硫代甲酸钠（DIDS）不敏感，对应于囊性纤维化跨膜电导调节因子（CFTR）样通道。对SPQ荧光的定量测量表明，只有DCTb细胞的顶端膜具有对福斯高林敏感的氯离子通道。逆转录聚合酶链反应（RT-PCR）实验表明两种培养物中均存在CFTR mRNA，而免疫染色实验显示CFTR仅在DCTb细胞中表达。讨论了不同类型通道的生理作用。
