Drewnowska K, Biber T U
Department of Physiology and Biophysics, Medical College of Virginia, Richmond 23298.
Am J Physiol. 1988 Jan;254(1 Pt 2):F95-104. doi: 10.1152/ajprenal.1988.254.1.F95.
Intracellular Cl activity was measured in isolated frog skin (Rana pipiens) with double-barrel microelectrodes. The initial rate of Cl uptake was measured in Cl-depleted cells on reexposure to Cl on apical or basolateral side. In skins with high and low conductance, cell CL activity increased 1.33 and 0.14 mM/s with apical reexposure and 5.03 and 0.30 mM/s with basolateral reexposure, respectively. The initial Cl uptake was reduced on the apical side by 93% with 10(-3) M DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) and on the basolateral side by 99% with 10(-3) M SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid) plus 10(-5) M bumetanide. The initial rate of Cl loss was measured when Cl was removed from the bath: addition of HCO3 to Cl- and HCO3-free solution caused an acceleration of Cl loss in absence but not in presence of DIDS on apical side. In contrast, Cl loss across the basolateral side was not enhanced by HCO3. In conclusion, Na-transporting cells have a substantial Cl permeability on both sides. HCO3-stimulated Cl loss provides evidence for Cl-HCO3 exchange and permits localization of this process in apical cell membranes of granular cells.
用双管微电极测量了离体青蛙皮肤（豹蛙）中的细胞内氯离子活性。在氯离子耗竭的细胞中，重新在顶端或基底外侧暴露于氯离子时，测量了氯离子摄取的初始速率。在高电导和低电导的皮肤中，顶端重新暴露时细胞氯离子活性分别以1.33和0.14 mM/s的速率增加，基底外侧重新暴露时分别以5.03和0.30 mM/s的速率增加。在顶端一侧，10(-3) M DIDS（4,4'-二异硫氰基芪-2,2'-二磺酸）使初始氯离子摄取减少93%，在基底外侧，10(-3) M SITS（4-乙酰氨基-4'-异硫氰基芪-2,2'-二磺酸）加10(-5) M布美他尼使初始氯离子摄取减少99%。当从浴液中去除氯离子时，测量了氯离子损失的初始速率：在顶端一侧，向无氯离子和无碳酸氢根的溶液中添加碳酸氢根会在不存在DIDS时加速氯离子损失，但存在DIDS时则不会。相反，基底外侧的氯离子损失不会因碳酸氢根而增强。总之，转运钠离子的细胞两侧都有相当大的氯离子通透性。碳酸氢根刺激的氯离子损失为氯离子-碳酸氢根交换提供了证据，并允许将该过程定位在颗粒细胞的顶端细胞膜中。
