cAMP-induced changes of apical membrane potentials of confluent H441 monolayers
cAMP-induced changes of apical membrane potentials of confluent H441 monolayers
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DOI：
10.1152/ajplung.00412.2002
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发表时间：
2003-08-01
影响因子：
4.9
通讯作者：
Matalon, S
中科院分区：
文献类型：
--
作者：
Lazrak, A;Matalon, S
我们记录了H441细胞[一种同时表现出上皮Na+（ENaC）和CFTR型通道的人肺细胞系]生长为汇合单层的顶端膜电位（V-a），在用10 μ M毛喉素灌注顶端膜之前、期间和之后，使用电流钳模式的微电极技术。当用正常林格溶液灌注时，细胞具有-43 +/- 10 mV的V-a（平均值+/- SD; n = 31）。用毛喉素灌注导致持续去极化25.0 +/- 3.5 mV（平均值+/- SD; n = 23），并增加了4.2 pS ENaC的数量、开放时间和开放概率。与之前的报告（Jiang J，Song C，Koller BH，Matthay MA和Verkman AS. Am J Physiol Cell Physiol 275：C1610-C1620，1998），没有观察到瞬时超极化。用10 μ M阿米洛利预处理单层或用N-甲基-D-葡糖胺取代浴溶液中的Na+离子，几乎完全阻止了毛喉素诱导的V-a去极化。这些结果表明，cAMP刺激Na+流入H441融合单层的结果从阿米洛利敏感的顶端Na+电导的激活，而不是从V-a超极化由于Cl-流入通过CFTR型通道。
We recorded apical membrane potentials (V-a) of H441 cells [a human lung cell line exhibiting both epithelial Na+ (ENaC) and CFTR-type channels] grown as confluent monolayers, using the microelectrode technique in current-clamp mode before, during, and after perfusion of the apical membranes with 10 muM forskolin. When perfused with normal Ringer solution, the cells had a V-a of -43 +/- 10 mV (means +/- SD; n = 31). Perfusion with forskolin resulted in sustained depolarization by 25.0 +/- 3.5 mV (means +/- SD; n = 23) and increased the number, open time, and the open probability of a 4.2-pS ENaC. In contrast to a previous report (Jiang J, Song C, Koller BH, Matthay MA, and Verkman AS. Am J Physiol Cell Physiol 275: C1610-C1620, 1998), no transient hyperpolarization was observed. The forskolin-induced depolarization of V-a was almost totally prevented by pretreatment of monolayers with 10 muM amiloride or by substitution of Na+ ions in the bath solution with N-methyl-D-glucamine. These findings indicate that cAMP stimulation of Na+ influx across H441 confluent monolayers results from activation of an amiloride-sensitive apical Na+ conductance and not from V-a hyperpolarization due to Cl- influx through CFTR-type channels.