Calcium influx mediated by the inwardly rectifying K+ channel Kir4.1 (KCNJ10) at low external K+ concentration
Calcium influx mediated by the inwardly rectifying K+ channel Kir4.1 (KCNJ10) at low external K+ concentration
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DOI：
10.1016/j.ceca.2006.12.004
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发表时间：
2007-09-01
期刊：
影响因子：
4
通讯作者：
Deitmer, Joachim W.
中科院分区：
文献类型：
--
作者：
Haertel, Kai;Singaravelu, Karthika;Deitmer, Joachim W.
具有Kir4.1 （KCNJ10）通道亚基异种表达的COS-1细胞，在细胞外K+浓度降低至2 mM或以下时，具有功能性Kir4.1通道并能够产生胞质Ca2+瞬态。这些Ca2+瞬态被外部Ba2+ (100 μ M)阻断。野生型小鼠（出生后第二周）急性脑干切片，加载荧光Ca2+指示剂俄勒冈绿BAPTA-1-AM，暴露于0.2 mM K+。在这些条件下，野生型小鼠的星形胶质细胞，而不是神经元，对胞浆Ca2+升高作出反应。这种星形胶质细胞特异性反应先前已被用于识别星形胶质细胞类型[j]。dalwig， H. Vitten， J.W. Deitmer，一种新的钡敏感钙流入大鼠星形胶质细胞。细胞钙28(2000)247-259]。在Kir4.1中敲除(Kir4。1(-/-))小鼠，应答细胞数量显著减少，应答细胞中的Ca2+瞬态明显小于野生型小鼠。我们的研究结果表明，Kir4.1通道是星形胶质细胞中观察到的Ca2+内流的分子底物(c) 2007 Elsevier Ltd。版权所有。
COS-1 cells with heterologeous expression of the Kir4.1 (KCNJ10) channel subunit, possess functional Kir4.1 channels and become capable to generating cytosolic Ca2+ transients, upon lowering of the extracellular K+ concentration to 2 mM or below. These Ca2+ transients are blocked by external Ba2+ (100 mu M). Acute brain stem slices from wild-type mice (second post-natal week), which were loaded with the fluorescent Ca2+ indicator Oregon Green BAPTA-1-AM, were exposed to 0.2 mM K+. Under these conditions astrocytes, but not neurons, responded with cytosolic Ca2+ elevations in wild-type mice. This astrocyte-specific response has previously been used to identify astroglial cells type [R. Dallwig, H. Vitten, J.W. Deitmer, A novel barium- sensitive calcium influx into rat astrocytes at low external potassium. Cell Calcium 28 (2000) 247-259]. In Kir4.1 knock-out (Kir4. 1(-/-)) mice, the number of responding cells was dramatically reduced and the Ca2+ transients in responding cells were significantly smaller than in wild-type mice. Our results indicate that Kir4.1 channels are the molecular substrate for the observed Ca2+ influx in astrocytes under (c) 2007 Elsevier Ltd. All rights reserved.