Prostaglandin E2 activates clusters of apical Cl- channels in principal cells via a cyclic adenosine monophosphate-dependent pathway.
Prostaglandin E2 activates clusters of apical Cl- channels in principal cells via a cyclic adenosine monophosphate-dependent pathway.
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前列腺素 E2 通过环磷酸腺苷依赖性途径激活主细胞中的顶端 Cl- 通道簇。
DOI：
10.1172/jci117037
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Eaton,DC
中科院分区：
文献类型：
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作者：
Ling,BN;Kokko,KE;Eaton,DC
我们检查了原代培养的兔皮质集合管主细胞上附着的细胞斑块。在基础状态下，9%(11/126)的斑块观察到心尖9-PSCl(-)选择性通道，通道数乘以开放概率(NP0)为0.56+/-0.21。该通道具有线性的电流-电压关系、接近静止膜电位的反转电位(EREV)、与电压无关的P0(0.30-0.70)以及在超极化电位下的复杂动力学(即猝发)。给予0.5微米前列腺素E_2(18/56)、10微米福司可林(23/36)或0.5毫米环腺苷(CAMP)30min后，NP0和通道频率均增加(25/41)。NP0的增加似乎主要是通过每片观察到的通道数(N)的增加来调节的，而不是P0的变化。在这些增加cAMP的动作后，N与根尖膜上通道的均匀分布不一致(P<；0.001)，而通道似乎成对聚集。心尖部0.5微米前列腺素E_2(12/91)、心尖部或基底外侧0.5微米前列腺素F2α(8/110)或0.25微米前列环素(细胞内钙释放物)(7/73)不增加NP0或通道频率。结论：(A)9-PS氯离子通道为根尖膜氯离子跨主细胞转运提供了一条传导途径。(B)基底侧PGE2激活通道是通过cAMP依赖的机制，而不是钙依赖的机制。(C)心尖通道成对聚集。(D)该通道的基线频率较低，EREV接近静息膜电位，在基础条件下对跨细胞氯离子通量无显著贡献。(E)产生cAMP的激动剂(即PGE2、精氨酸加压素)会增加心尖部的氯离子转运，其方向由心尖膜电位决定。
We examined cell-attached patches on principal cells of primary cultured, rabbit cortical collecting tubules. Under basal conditions, apical 9-pS Cl(-)-selective channels were observed in 9% of patches (11/126), and number of channels times open probability (NP0) was 0.56 +/- 0.21. The channel had a linear current-voltage relationship, reversal potential (Erev) near resting membrane potential, a P0 (0.30-0.70) that was independent of voltage, and complicated kinetics (i.e., bursting) at hyperpolarized potentials. NP0 and channel frequency were increased after 30 min of basolateral exposure to 0.5 microM PGE2 (18/56), 10 microM forskolin (23/36), or 0.5 mM dibutyryl cyclic adenosine monophosphate (cAMP) (25/41). Increases in NP0 appeared to be mediated primarily through an increase in the number of observed channels per patch (N), not changes in P0. After these cAMP-increasing maneuvers, N was inconsistent with a uniform distribution of channels in the apical membrane (P < 0.001), but rather the channels appeared to be clustered in pairs. Apical 0.5 microM PGE2 (12/91), apical or basolateral 0.5 microM PGF2 alpha (8/110), or 0.25 microM thapsigargin (releaser of intracellular Ca2+ stores) (7/73) did not increase NP0 or channel frequency. Conclusions: (a) 9-pS Cl- channels provide a conductive pathway for apical membrane Cl- transport across principal cells. (b) Channel activation by basolateral PGE2 is mediated via a cAMP-, but not a Ca(2+)-dependent mechanism. (c) Apical channels are clustered in pairs. (d) With its low baseline frequency and Erev near resting membrane potential, this channel would not contribute significantly to transcellular Cl- flux under basal conditions. (e) However, cAMP-producing agonists (i.e., PGE2, arginine vasopressin) would increase apical Cl- transport with the direction determined by the apical membrane potential.