Jiang X, Ingbar D H, O'Grady S M
Departments of Physiology and Medicine, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Am J Physiol. 1998 Dec;275(6):C1610-20. doi: 10.1152/ajpcell.1998.275.6.C1610.
Alveolar epithelial cells were isolated from adult Sprague-Dawley rats and grown to confluence on membrane filters. Most of the basal short-circuit current (Isc; 60%) was inhibited by amiloride (IC50 0. 96 microM) or benzamil (IC50 0.5 microM). Basolateral addition of terbutaline (2 microM) produced a rapid decrease in Isc, followed by a slow recovery back to its initial amplitude. When Cl- was replaced with methanesulfonic acid, the basal Isc was reduced and the response to terbutaline was inhibited. In permeabilized monolayer experiments, both terbutaline and amiloride produced sustained decreases in current. The current-voltage relationship of the terbutaline-sensitive current had a reversal potential of -28 mV. Increasing Cl- concentration in the basolateral solution shifted the reversal potential to more depolarized voltages. These results were consistent with the existence of a terbutaline-activated Cl- conductance in the apical membrane. Terbutaline did not increase the amiloride-sensitive Na+ conductance. We conclude that beta-adrenergic stimulation of adult alveolar epithelial cells results in an increase in apical Cl- permeability and that amiloride-sensitive Na+ channels are not directly affected by this stimulation.
从成年Sprague-Dawley大鼠分离肺泡上皮细胞，并使其在膜滤器上生长至汇合。大部分基础短路电流（Isc；60%）被氨氯吡咪（IC50 0.96微摩尔）或苄甲咪（IC50 0.5微摩尔）抑制。在基底外侧加入特布他林（2微摩尔）使Isc迅速降低，随后缓慢恢复至初始幅度。当用甲磺酸替代Cl-时，基础Isc降低，对特布他林的反应受到抑制。在通透单层实验中，特布他林和氨氯吡咪均使电流持续降低。特布他林敏感电流的电流-电压关系的反转电位为-28 mV。增加基底外侧溶液中的Cl-浓度使反转电位向更去极化的电压移动。这些结果与顶端膜中存在特布他林激活的Cl-电导一致。特布他林未增加氨氯吡咪敏感的Na+电导。我们得出结论，成年肺泡上皮细胞的β-肾上腺素能刺激导致顶端Cl-通透性增加，且氨氯吡咪敏感的Na+通道不受该刺激直接影响。
