Potassium dependence of Na-Cl cotransport in dog tracheal epithelium.
Potassium dependence of Na-Cl cotransport in dog tracheal epithelium.
复制标题
狗气管上皮中 Na-Cl 共转运的钾依赖性。
DOI：
10.1152/ajplung.1991.261.4.l290
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Widdicombe,JH
中科院分区：
文献类型：
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作者：
Fong,P;Chao,AC;Widdicombe,JH
在狗气管上皮的汇合原代培养物中，我们测试了 Cl 穿过基底外侧膜的进入是否是通过与 K 的共转运来进行的。采用了两种方法。首先，我们测量了 K 通道抑制剂 Ba2+ 对短路电流 (Isc) 的抑制作用。与 Na-K-2Cl 共转运一致，最大剂量的 Ba2+ 抑制先前刺激分泌 Cl 的组织中六分之五的 Isc；如果 NaCl 共转运是进入机制，则只有三分之二的 Isc 对 Ba2+ 敏感。其次，我们测量了基底外侧 86Rb 的摄取，并证明了布美他尼（一种其他组织中 Na-K-2Cl 共转运的抑制剂）的抑制作用。布美他尼的抑制程度与以 Isc 测量的 Cl 分泌水平一致。 86Rb 的摄取也通过去除 Na 或 Cl 而减少，并且在这些条件下，布美他尼不会进一步抑制 Rb 的摄取。这些结果表明，在 Cl 分泌过程中，Cl 穿过气管上皮基底外侧膜进入的过程是 Na-K-2Cl，而不是 Na-Cl 共转运。
In confluent primary cultures of dog tracheal epithelium, we tested whether Cl entry across the basolateral membrane is by cotransport with K. Two approaches were taken. First, we measured the inhibition of short-circuit current (Isc) by the K channel inhibitor, Ba2+. Consistent with Na-K-2Cl cotransport, maximal doses of Ba2+ inhibited five-sixths of Isc in tissues previously stimulated to secrete Cl; only two-thirds of Isc should be sensitive to Ba2+ if NaCl cotransport is the entry mechanism. Second, we measured basolateral 86Rb uptake and demonstrated inhibition by bumetanide, an inhibitor of Na-K-2Cl cotransport in other tissues. The degree of inhibition by bumetanide was consistent with the levels of Cl secretion measured as Isc. Uptake of 86Rb was also reduced by removal of Na or Cl, and under these conditions Rb uptake was not further inhibited by bumetanide. These results suggest that the process responsible for Cl entry across the basolateral membrane of tracheal epithelium during Cl secretion is Na-K-2Cl rather than Na-Cl cotransport.