Is the secretory K channel in the rat CCT ROMK?
Is the secretory K channel in the rat CCT ROMK?
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大鼠 CCT ROMK 中的分泌 K 通道是吗？
DOI：
10.1152/ajprenal.1997.273.3.f404
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Frindt,G
中科院分区：
文献类型：
--
作者：
Palmer,LG;Choe,H;Frindt,G
研究了大鼠皮质集小管顶膜低导分泌K （SK）通道的生物物理特性，并将其与卵母细胞中表达的ROMK家族克隆肾K通道进行了比较。在室温下，在移液管中加入140 mM K和110 mM阳离子时，SK通道向内的单通道电导为K 36 +/- 1 pS， NH4 41 +/- 2 pS, Tl 22 +/- 3 pS。移液管中K和Tl的反转电位几乎相同，但NH4的位移为-60 mV。当K为渗透离子时，通道动力学可描述为单打开状态（平均打开时间为24 ms）和两个关闭状态（平均关闭时间为1.6 ms和65 ms）。当Tl为渗透离子（平均打开时间为6.6 ms，无长闭态）和NH4为渗透离子（平均打开时间为3.0 ms，较普遍的长闭态）时，SK的动力学发生了变化。因此，通道的门控动力学在很大程度上取决于传导离子的性质。SK通道的性质与爪蟾卵母细胞中表达的ROMK2非常相似，并在相似的条件下测量，表明这些通道是相同的。
The biophysical properties of low-conductance secretory K (SK) channels in the apical membrane of the rat cortical collecting tubule were examined to compare these properties with those of the cloned renal K channels of the ROMK family expressed in oocytes. At room temperature, with the tubule superfused with 140 mM K and 110 mM cation in the pipette, the inward single-channel conductance of the SK channels was 36 +/- 1 pS for K, 41 +/- 2 pS for NH4, and 22 +/- 3 pS for Tl. The reversal potential was nearly the same for K and Tl in the pipette but was shifted by -60 mV for NH4. The kinetics of the channel when K was the permeant ion could be described by a single open state (mean open time, 24 ms) and two closed states (mean closed times, 1.6 and 65 ms). The kinetics of SK changed when Tl was the permeant ion (mean open times of 6.6 ms and no long closed state) and when NH4 was the permeant ion (mean open time of 3.0 ms and a more prevalent long closed state). Thus the gating kinetics of the channel depend strongly on the nature of the conducted ion. The properties of SK channels were quite similar to those of ROMK2 expressed in Xenopus oocytes and measured under similar conditions, suggesting that these channels are identical.