An inward rectifier K+ channel at the basolateral membrane of the mouse distal convoluted tubule:: similarities with Kir4-Kir5.1 heteromeric channels
An inward rectifier K+ channel at the basolateral membrane of the mouse distal convoluted tubule:: similarities with Kir4-Kir5.1 heteromeric channels
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DOI：
10.1113/jphysiol.2001.012961
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发表时间：
2002-01-15
影响因子：
5.5
通讯作者：
Teulon, J
中科院分区：
文献类型：
--
作者：
Lourdel, S;Paulais, M;Teulon, J
在本研究中，使用膜片钳方法研究了远曲小管（DCT）基底外侧膜中的K+通道。此外，Kir4.1。采用RT-PCR和免疫组织化学（Kir4.1）检测Kir4.2和Kir5.1内向整流通道。从胶原酶处理的小鼠肾脏显微解剖DCTs。在约50%的DCT基底外侧膜细胞附着斑块中检测到一种类型的K+通道；该通道向内整流，并且在外部[K+]为145 mm时具有类似于40 pS的向内电导（δ (in)）。当内外贴片暴露于不含Mg2+的介质中时，电流-电压关系为线性关系。浓度为1.2 mm的Mg2+显著降低了向外电导（δ (out)），产生δ (in)/ δ (out)比值接近4.7。多阳离子精胺（5 × 10(-7) m）降低了50%的打开概率（P-o）。通道活性依赖于细胞内pH值，酸性pH值降低，碱性pH值升高，P-o。内部ATP （2 mm）和Ca2+（高达10(-3)m）没有影响。当贴片内侧暴露于Mg2+时，通道活性不可逆地下降。DCT中均检测到Kir4.1、Kir4.2和Kir5.1 mrna。Kir4.1蛋白与DCT特异性的Na+- cl共转运蛋白共定位，位于基底外侧膜上。DCT K+通道不同于其他功能确定的肾K+通道，其受精胺的抑制和对内部ATP和Ca2+的不敏感。在目前的知识状态下，通道类似于Kir4.1-Kir5。Kir4.1和Kir4.2- kir5.1异质通道，而不是Kir4.1和Kir4.2同质通道。
In this study, K+ channels present in the basolateral membrane of the distal convoluted tubule (DCT) were investigated using patch-clamp methods. In addition, Kir4.1. Kir4.2 and Kir5.1 inward rectifier channels were investigated using RT-PCR and immunohistochemistry (Kir4.1). DCTs were microdissected from collagenase-treated mouse kidneys. One type of K+ channel was detected in about 50 % of cell-attached patches from the DCT basolateral membrane; this channel was inwardly rectifying and had an inward conductance (delta(in)) of similar to40 pS at an external [K+] of 145 mm. The current-voltage relationship was linear when inside-out patches were exposed to a Mg2+-free medium. Mg2+ at a concentration of 1.2 mm considerably reduced the outward conductance (delta(out)), yielding a delta(in)/delta(out) ratio of similar to4.7. The polycation spermine (5 X 10(-7) m) reduced the open probability (P-o) by 50 %. Channel activity was dependent upon the intracellular pH, with acid pH decreasing, and basic pH increasing, P-o. Internal ATP (2 mm) and Ca2+ (up to 10(-3) m) had no effect. Channel activity declined irreversibly when the inner side of the patch was exposed to Mg2+. Kir4.1, Kir4.2 and Kir5.1 mRNAs were all detected in the DCT. The Kir4.1 protein co-localised with the Na+-Cl-cotransporter, which is specific to the DCT, and was located on basolateral membranes. The DCT K+ channel differs from other functionally identified renal K+ channels with regard to its inhibition by spermine and insensitivity to internal ATP and Ca2+. At the current state of knowledge, the channel is similar to Kir4.1-Kir5.l and Kir4.2-Kir5.1 heteromeric channels, but not to Kir4.1 or Kir4.2 homomeric channels.