Butt A G, Clapp W L, Frizzell R A
Department of Physiology, University of Alabama, Birmingham 35294.
Am J Physiol. 1990 Apr;258(4 Pt 1):C630-8. doi: 10.1152/ajpcell.1990.258.4.C630.
Increased basolateral membrane K conductance accompanies stimulation of Cl secretion across canine trachea. To assess the K conductance properties, we permeabilized the apical membranes with amphotericin B and monitored the current and conductance caused by K flow across the basolateral membranes. Under basal unstimulated conditions, two K conductances could be distinguished by blockers. One was inhibited only by barium; the other was sensitive also to quinidine and lidocaine. The permeabilities of the basal conductance pathways to K and Rb were similar (PK/PRb approximately equal to 1.5). The secretory agonist, epinephrine, selectively increased the quinidine-insensitive conductance, implicating it in the Cl secretory response. Cell swelling induced a third conductance with a low permeability to Rb (PK/PRb approximately equal to 10) that was quinidine sensitive. In tissues not treated with amphotericin, neither quinidine nor Rb-for-K replacement inhibited transepithelial Cl secretion. Thus neither of the quinidine-sensitive K conductances (basal or swelling induced) contribute to the increase in basolateral K conductance during Cl secretion. Cell shrinkage inhibited all three conductances and secretion, suggesting that the initial priority of the cell is volume regulation.
犬气管氯离子分泌增加时，基底外侧膜钾离子电导也会增加。为评估钾离子电导特性，我们用两性霉素B使顶端膜通透，监测钾离子跨基底外侧膜流动所引起的电流和电导。在基础未刺激条件下，两种钾离子电导可通过阻滞剂区分。一种仅被钡离子抑制；另一种对奎尼丁和利多卡因也敏感。基础电导途径对钾离子和铷离子的通透性相似（PK/PRb约等于1.5）。分泌激动剂肾上腺素选择性增加了对奎尼丁不敏感的电导，表明其参与了氯离子分泌反应。细胞肿胀诱导出第三种对铷离子通透性低（PK/PRb约等于10）且对奎尼丁敏感的电导。在未用两性霉素处理的组织中，奎尼丁和用铷离子替代钾离子均不抑制跨上皮氯离子分泌。因此，在氯离子分泌过程中，两种对奎尼丁敏感的钾离子电导（基础的或肿胀诱导的）均不导致基底外侧钾离子电导增加。细胞皱缩抑制了所有三种电导及分泌，提示细胞的首要任务是调节体积。
