A potassium channel in the apical membrane of rabbit thick ascending limb of Henle's loop.
A potassium channel in the apical membrane of rabbit thick ascending limb of Henle's loop.
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兔亨勒袢升肢厚层顶膜中的钾通道。
DOI：
10.1152/ajprenal.1990.258.2.f244
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Giebisch,G
中科院分区：
文献类型：
--
作者：
Wang,WH;White,S;Geibel,J;Giebisch,G
应用膜片钳技术研究了兔肾亨利袢（TAL）升支端膜钾通道的活动。在细胞贴附贴片中，在浴中加入NaCl林格或高K+溶液，在移液管中加入140 mM K+，在22 ℃下观察到向内整流K+通道，向内斜率电导为22.0 +/- 0.5 pS，向外斜率电导为10.2 +/- 0.3 pS（n = 15）。该通道对K+具有高度选择性，计算的K（+）与Na+的渗透率比为20：1（n = 4）。通道的开放概率（Po）为0.89 +/-0.03（n = 15），并且不依赖于电压。在140 mM的K+在浴和移液管的解决方案中，由内而外的补丁，PO和电导的通道是类似的细胞附着的补丁。添加0.1 mM Ba 2+的移液管解决方案减少PO的通道中的电压依赖性的方式。降低浴溶液的pH值从7.4到6.9或增加Ca 2+浓度从0到0.5 mM的内翻补丁没有改变无论是PO或电导的通道。向浴槽溶液中添加2 mM ATP完全抑制通道活性。这种ATP诱导的抑制是完全可逆的，并被认为是依赖于ATP与ADP的比例，因为加入1 mM ADP的浴溶液解除ATP诱导的封锁。这种小电导K+通道的特性使其成为K+穿过兔肾TAL顶膜再循环的可能候选者。ATP和ADP可能是通道活性的细胞内调节剂。
We used the patch-clamp technique to study the activity of single potassium channels in the apical membrane of isolated thick ascending limbs of Henle's loop (TAL) of rabbit kidneys. In cell-attached patches with NaCl Ringer or high-K+ solution in the bath and 140 mM K+ in the pipette, an inwardly rectifying K+ channel was observed with an inward slope conductance of 22.0 +/- 0.5 pS and outward slope conductance of 10.2 +/- 0.3 pS at 22 degrees C (n = 15). The channel was highly selective for K+, with a calculated permeability ratio for K(+)-to-Na+ of 20:1 (n = 4). The open probability (Po) of the channel was 0.89 +/- 0.03 (n = 15) and was not voltage dependent. In inside-out patches with 140 mM K+ in both the bath and the pipette solutions, both Po and conductance of the channel were similar to that in cell-attached patches. Addition of 0.1 mM Ba2+ to the pipette solution reduced Po of the channel in a voltage-dependent manner. Lowering the pH of the bath solution from 7.4 to 6.9 or increasing Ca2+ concentration from 0 to 0.5 mM in inside-out patches did not alter either Po or conductance of the channel. Addition of 2 mM ATP to the bath solution completely inhibited channel activity. This ATP-induced inhibition was fully reversible and was found to be dependent on the ratio of ATP to ADP, since adding 1 mM ADP to the bath solution relieved the ATP-induced blockade. The property of this small-conductance K+ channel make it a likely candidate for recycling of K+ across the apical membrane of TAL of the rabbit kidney. ATP and ADP are possible intracellular regulators of the channel's activity.