CALCIUM AND CAMP ACTIVATE DIFFERENT CHLORIDE CHANNELS IN THE APICAL MEMBRANE OF NORMAL AND CYSTIC-FIBROSIS EPITHELIA
CALCIUM AND CAMP ACTIVATE DIFFERENT CHLORIDE CHANNELS IN THE APICAL MEMBRANE OF NORMAL AND CYSTIC-FIBROSIS EPITHELIA
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DOI：
10.1073/pnas.88.14.6003
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发表时间：
1991-07-01
影响因子：
11.1
通讯作者：
WELSH, MJ
中科院分区：
文献类型：
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作者：
ANDERSON, MP;WELSH, MJ
遗传性疾病囊性纤维化（CF）导致几种上皮细胞中Cl-转运减少。在CF气道上皮细胞中，顶膜Cl-通道的cAMP依赖性调节是有缺陷的;结果，CF上皮细胞不能分泌Cl-。相反，钙离子刺激的氯离子分泌是完整的CF气道上皮细胞，因此有可能绕过CF氯离子分泌缺陷。对于控制氯离子分泌的氯离子通道来说，它必须位于顶膜中。为了专门研究顶端膜Cl-通道，我们研究了在可渗透的过滤器支持物上生长的细胞，并测量了跨顶端膜的Cl-电流。我们发现，Ca ~（2+）和cAMP激活不同的Cl-通道在顶端膜。(i)Ca 2+激活的Cl-通道存在于气道顶膜，而不存在于肠上皮细胞。(ii)CF气道上皮细胞cAMP激活的Cl-通道存在缺陷，而Ca ~（2+）激活的Cl-通道无缺陷。(iii)4，4 '-二异硫氰酸基-2，2'-二苯乙烯二磺酸盐可阻断Ca 2+激活的Cl-通道，但不阻断cAMP激活的Cl-通道。(iv)Ca ~（2+）和cAMP激活的根尖通道具有不同的阴离子渗透性。(v)两种第二信使的增加产生了Cl-电流的附加增加。这些结果也解释了令人困惑的观察，即Ca ~（2+）刺激的Cl ~-分泌在CF肠中是缺陷的：可以绕过CF气道中Cl ~-分泌缺陷的Ca ~（2+）激活的Cl ~-通道在肠上皮细胞的顶膜上缺失。
The genetic disease cystic fibrosis (CF) causes decreased Cl- transport in several epithelia. cAMP-dependent regulation of apical membrane Cl- channels is defective in CF airway epithelia; as a result, CF epithelia fail to secrete Cl-. In contrast, Ca2+-stimulated Cl- secretion is intact in CF airway epithelia and thus has the potential to bypass the CF Cl- secretory defect. For a Cl- channel to govern Cl- secretion, it must be located in the apical membrane. To specifically investigate apical membrane Cl- channels, we studied cells grown on permeable filter supports and measured Cl- currents across the apical membrane. We found that Ca2+ and cAMP activate different Cl- channels in the apical membrane. (i) Ca2+-activated Cl- channels were present in the apical membrane of airway but not in intestinal epithelia. (ii) cAMP- but not Ca2+-activated Cl- channels were defective in CF airway epithelia. (iii) Ca 2+- but not cAMP-activated Cl- channels were blocked by 4,4'-diisothiocyanato-2,2'-stilbenedisulfonate. (iv) Ca2+- and cAMP-activated apical channels had different anion permeabilities. (v) An increase in both second messengers produced an additive increase in Cl- current. These results also explain the puzzling observation that Ca2+-stimulated Cl- secretion is defective in CF intestine: the Ca2+-activated Cl- channels that could circumvent the Cl- secretory defect in CF airway are missing from the apical membrane of intestinal epithelia.