Gramicidin-Perforated Patch Analysis on HCO3− Secretion Through a Forskolin-Activated Anion Channel in Rat Parotid Intralobular Duct Cells
Gramicidin-Perforated Patch Analysis on HCO3− Secretion Through a Forskolin-Activated Anion Channel in Rat Parotid Intralobular Duct Cells
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通过短杆菌肽穿孔贴片分析大鼠腮腺小叶内导管细胞中毛喉素激活阴离子通道的 HCO3− 分泌
DOI：
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发表时间：
2001
影响因子：
2.4
通讯作者：
Y. Shiba
中科院分区：
文献类型：
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作者：
C. Hirono;T. Nakamoto;M. Sugita;Y. Iwasa;Y. Akagawa;Y. Shiba
抽象的。研究了毛喉素诱导的阴离子电流和去极化，以阐明大鼠腮腺小叶内导管细胞中HCO 3 −分泌的机制。在K+的平衡电位下测量细胞的阴离子电流，使用可忽略不计地影响细胞内阴离子浓度的短杆菌肽穿孔贴片技术。毛喉素诱导的阴离子电流持续存在，并被格列本脲（200 μm）显著抑制（54%），格列本脲是囊性纤维化跨膜传导调节因子（CFTR）Cl−通道的阻滞剂。通过加入1 mm醋甲唑胺（一种碳酸酐酶抑制剂）和去除外部HCO 3 −，阴离子电流被显著抑制。毛喉素在电流钳模式下使细胞去极化。添加醋甲唑胺和去除外部HCO 3-显著降低去极化水平。这些结果表明，阴离子通道（主要是位于管腔膜中的CFTR Cl−通道）的激活和胞质HCO 3 −的产生诱导了内向阴离子电流和导致的去极化。抑制Na+-K+-2Cl−协同转运蛋白和Cl−-HCO 3 −交换蛋白对电流或去极化没有显著影响，表明通过Na+-K+-2Cl−协同转运蛋白或Cl−-HCO 3 −交换蛋白摄取Cl−不参与反应。综上所述，我们得出结论，毛喉素激活细胞内产生的HCO 3 −的向外运动（可能是分泌），但由于腮腺导管细胞中缺乏活跃的Cl−转运，因此不能激活Cl−，并且短杆菌肽穿孔贴片法对于分析阴离子转运非常有用。
Abstract. Forskolin-induced anion currents and depolarization were investigated to clarify the mechanism of HCO3− secretion in the intralobular duct cells of rat parotid glands. Anion currents of the cells were measured at the equilibrium potential of K+, using a gramicidin-perforated patch technique that negligibly affects intracellular anion concentration. The forskolin-induced anion current was sustained and significantly (54%) suppressed by glibenclamide (200 μm), a blocker of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. The anion current was markedly suppressed by addition of 1 mm methazolamide, a carbonic anhydrase inhibitor, and removal of external HCO3−. Forskolin depolarized the cells in the current-clamp mode. Addition of methazolamide and removal of external HCO3− significantly decreased the depolarizing level. These results suggest that activation of anion channels (mainly the CFTR Cl− channel located in luminal membranes) and production of cytosolic HCO3− induce the inward anion current and resulting depolarization. Inhibition of the Na+-K+-2Cl− cotransporter and the Cl−-HCO3− exchanger had no significant effect on the current or depolarization, indicating that the uptake of Cl− via the Na+-K+-2Cl− cotransporter or the Cl−-HCO3− exchanger is not involved in the responses. Taken together, we conclude that forskolin activates the outward movement (probably secretion) of HCO3− produced intracellularly, but not of Cl− due to lack of active Cl− transport in parotid duct cells, and that the gramicidin-perforated patch method is very useful to analyze anion transport.
DOI：
10.1073/pnas.91.12.5340
发表时间：
1994-06-07
影响因子：
11.1
作者：
POULSEN, JH;FISCHER, H;MACHEN, TE
通讯作者：
MACHEN, TE