Two types of K+ channel in thick ascending limb of rat kidney.
Two types of K+ channel in thick ascending limb of rat kidney.
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大鼠肾升肢粗部的两种K通道。
DOI：
10.1152/ajprenal.1994.267.4.f599
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Wang,WH
中科院分区：
文献类型：
--
作者：
Wang,WH
应用膜片钳技术对大鼠肾厚升肢（TAL）的K+通道进行了研究。两种类型的K+通道，低电导和中电导K+通道，在细胞附着和内向外斑块中都被鉴定出来。我们证实了先前报道的中间电导K+通道（72 pS），它被毫摩尔细胞ATP、酸性pH、Ba2+和奎尼丁抑制(4)。我们现在报告在TAL的顶端膜上发现第二个K+通道。该低电导K+通道的斜率电导为30 pS，在细胞附着斑块中其打开概率为0.80。该通道不依赖于电压，并且在槽中应用2毫米ATP抑制通道活性。此外，250 microM的格列本脲是一种atp敏感的K+通道抑制剂，可以阻断通道活性，而相同浓度的格列本脲对72-pS K+通道没有抑制作用。30-pS K+通道活性在斑块切除后迅速下降（通道下降）。应用0.1 mM ATP和腺苷3′，5′-环单磷酸腺苷（cAMP）依赖性蛋白激酶A （PKA）的催化亚基可恢复通道活性。此外，在细胞贴片中加入0.1 mM的8-（4-氯苯基硫磷）- camp或50-100 pM的抗利尿激素可增加通道活性。综上所述，大鼠肾TAL尖膜存在两种类型的K+通道，PKA在调节低电导K+通道活性中起重要作用。
We have used the patch-clamp technique to study the apical K+ channels in the thick ascending limb (TAL) of the rat kidney. Two types of K+ channels, a low-conductance and an intermediate-conductance K+ channel, were identified in both cell-attached and inside-out patches. We confirmed the previously reported intermediate-conductance K+ channel (72 pS), which is inhibited by millimolar cell ATP, acidic pH, Ba2+, and quinidine (4). We now report a second K+ channel in apical membrane of the TAL. The slope conductance of this low-conductance K+ channel is 30 pS, and its open probability is 0.80 in cell-attached patches. This channel is not voltage dependent, and application of 2 mM ATP in the bath inhibits channel activity in inside-out patches. In addition, 250 microM glyburide, an ATP-sensitive K+ channel inhibitor, blocks channel activity, whereas the same concentration of glyburide has no inhibitory effect on the 72-pS K+ channel. Channel activity of the 30-pS K+ channel decreases rapidly upon excision of patches (channel run down). Application of 0.1 mM ATP and the catalytic subunit of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) restores channel activity. Furthermore, addition of 0.1 mM 8-(4-chlorophenylthio)-cAMP or 50-100 pM vasopressin in the cell-attached patches increases channel activity. In conclusion, two types of K+ channels are present in the apical membrane of TAL of rat kidney, and PKA plays an important role in modulation of the low-conductance K+ channel activity.