Role of Ca2+/CaMK II in Ca(2+)-induced K+ channel inhibition in rat CCD principal cell.
Role of Ca2+/CaMK II in Ca(2+)-induced K+ channel inhibition in rat CCD principal cell.
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Ca2 /CaMK II 在 Ca(2 ) 诱导的大鼠 CCD 主细胞 K 通道抑制中的作用。
DOI：
10.1152/ajprenal.1995.268.2.f211
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Giebisch,G
中科院分区：
文献类型：
--
作者：
Kubokawa,M;Wang,W;McNicholas,CM;Giebisch,G
细胞内Ca ~（2+）浓度增加可抑制大鼠皮质集合管（CCD）顶端低电导K ~+通道。这种作用已被证明至少部分是由蛋白激酶C（PKC）的激活介导的。本研究应用膜片钳技术研究了钙/钙调素依赖性蛋白激酶II（CaMK II）在介导Ca（2+）抑制效应中的作用。在大鼠肾小管的主细胞的细胞附着的补丁，在400 nM的细胞内Ca 2+浓度通过使用1 μ M离子霉素的钳位降低通道活性的26.5%的控制值。通道活性进一步降低，至对照值的8.8%，观察到佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA），一种已知激活PKC的试剂。用KN-62（CaMK II抑制剂）或GF-109203 X（PKC抑制剂）预处理细胞可减弱Ca 2+对K+通道活性的抑制作用（分别为对照值的83.2%和50.7%）。即使在KN-62的存在下，添加10 μ M PMA也显著降低通道活性至对照值的57.2%。同时与KN-62和GF-109203 X孵育可完全消除Ca（2+）诱导的抑制作用。在由内而外的贴片中，在PKC抑制剂存在下加入20微克/毫升CaMK II将通道活性降低至对照值的66.2%。提示CaMK Ⅱ参与介导Ca ~（2+）对大鼠CCD顶端K ~+通道活性的抑制。
The apical low-conductance K+ channel of rat cortical collecting duct (CCD) is inhibited by increased intracellular Ca2+ concentrations. This effect has been shown to be mediated at least in part by activation of protein kinase C (PKC). In the present study, we used the patch-clamp technique to examine the role of Ca2+/calmodulin-dependent protein kinase II (CaMK II) in mediating the Ca(2+)-induced inhibitory effect. In cell-attached patches of principal cells of rat tubules, clamping of intracellular Ca2+ concentration at 400 nM by using 1 microM ionomycin reduced channel activity to 26.5% of the control value. A further reduction in channel activity, to 8.8% of the control value, was observed following the addition of phorbol 12-myristate 13-acetate (PMA), an agent known to activate PKC. Pretreatment of cells with KN-62 (CaMK II inhibitor) or GF-109203X (PKC inhibitor) attenuated the inhibitory effect of Ca2+ on K+ channel activity (83.2 and 50.7% of the control value, respectively). Even in the presence of KN-62, addition of 10 microM PMA significantly decreased channel activity to 57.2% of the control value. The Ca(2+)-induced inhibition was completely abolished by simultaneous incubation with both KN-62 and GF-109203X. In inside-out patches, addition of 20 micrograms/ml CaMK II in the presence of a PKC inhibitor reduced channel activity to 66.2% of control values. It is concluded that CaMK II is involved in mediating the Ca(2+)-induced inhibition of the activity of the apical K+ channel of rat CCD.