Zacopride selectively activates the Kir2.1 channel via a PKA signaling pathway in rat cardiomyocytes
Zacopride selectively activates the Kir2.1 channel via a PKA signaling pathway in rat cardiomyocytes
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Zacopride 通过 PKA 信号通路选择性激活大鼠心肌细胞中的 Kir2.1 通道
DOI：
10.1007/s11427-013-4531-z
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发表时间：
2013-09-01
影响因子：
9.1
通讯作者：
Wu BoWei
中科院分区：
文献类型：
--
作者：
Zhang Li;Liu QingHua;Wu BoWei
我们最近报道了zacopride是一种选择性内向整流钾电流（IK1）通道激动剂，可抑制室性心律失常而不影响心房心律失常。本研究旨在探讨扎可夫利独特的药理学性质。采用全细胞膜片钳技术研究大鼠心房肌细胞IK1电流和Kir2电流。x电流在人胚胎肾(HEK)-293细胞中转染了内向钾通道（Kir）2.1、Kir2.2、Kir2.3或突变Kir2.1（磷酸化位点S425L）。Western免疫印迹法测定Kir2的相对蛋白表达水平。X在大鼠心房和心室。结果表明，扎可普利对心房肌细胞IK1和跨膜电位无明显影响。在HEK293细胞中，zacopride在−50 mV下使Kir2.1同质通道增加40.7%±9.7%，但对Kir2.2和Kir2.3同质通道以及Kir2.1-Kir2.2、Kir2.1-Kir2.3和Kir2.2-Kir2.3异质通道没有影响。Western免疫印迹显示，大鼠心房和心室Kir2.3蛋白表达水平相似，但心房Kir2.1蛋白表达水平仅为心室的25%。5-羟色胺（5-HT）3受体在HEK293细胞中未检测到，而5-HT4受体在HEK293细胞中表达较弱。zacopride在这些细胞中的Kir2.1激活作用通过抑制蛋白激酶A （PKA）而不是PKC或PKG而被消除。此外，zacopride不激活HEK293细胞中的Kir2.1突变体通道，而是通过PKA依赖性途径选择性地激活Kir2.1同源通道，而不依赖于5-HT受体。
We recently reported that zacopride is a selective inward rectifier potassium current (IK1) channel agonist, suppressing ventricular arrhythmias without affecting atrial arrhythmias. The present study aimed to investigate the unique pharmacological properties of zacopride. The whole-cell patch-clamp technique was used to study IK1 currents in rat atrial myocytes and Kir2.x currents in human embryonic kidney (HEK)-293 cells transfected with inward rectifier potassium channel (Kir)2.1, Kir2.2, Kir2.3, or mutated Kir2.1 (at phosphorylation site S425L). Western immunoblots were performed to estimate the relative protein expression levels of Kir2.x in rat atria and ventricles. Results showed that zacopride did not affect the IK1 and transmembrane potential of atrial myocytes. In HEK293 cells, zacopride increased Kir2.1 homomeric channels by 40.7%±9.7% at −50 mV, but did not affect Kir2.2 and Kir2.3 homomeric channels, and Kir2.1-Kir2.2, Kir2.1-Kir2.3 and Kir2.2-Kir2.3 heteromeric channels. Western immunoblots showed that similar levels of Kir2.3 protein were expressed in rat atria and ventricles, but atrial Kir2.1 protein level was only 25% of that measured in the ventricle. In addition, 5-hydroxytryptamine (5-HT)3 receptor was undetectable, whereas 5-HT4 receptor was weakly expressed in HEK293 cells. The Kir2.1-activating effect of zacopride in these cells was abolished by inhibition of protein kinase A (PKA), but not PKC or PKG. Furthermore, zacopride did not activate the mutant Kir2.1 channel in HEK293 cells but selectively activated the Kir2.1 homomeric channel via a PKA-dependent pathway, independent to that of the 5-HT receptor.