Descending vasa recta endothelia express inward rectifier potassium channels.
Descending vasa recta endothelia express inward rectifier potassium channels.
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降直血管内皮细胞表达内向整流钾通道。
DOI：
10.1152/ajprenal.00278.2007
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Pallone,ThomasL
中科院分区：
文献类型：
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作者：
Cao,Chunhua;Lee-Kwon,Whaseon;Payne,Kristie;Edwards,Aurelie;Pallone,ThomasL
Descending vasa recta (DVR) are capillary-sized microvessels that supply blood flow to the renal medulla. They are composed of contractile pericytes and endothelial cells. In this study, we used the whole cell patch-clamp method to determine whether inward rectifier potassium channels (KIR) exist in the endothelia, affect membrane potential, and modulate intracellular Ca2+concentration ([Ca2+]cyt). The endothelium was accessed for electrophysiology by removing abluminal pericytes from collagenase-digested vessels. KIRcurrents were recorded using symmetrical 140 mM K+solutions that served to maximize currents and eliminate cell-to-cell coupling by closing gap junctions. Large, inwardly rectifying currents were observed at membrane potentials below the equilibrium potential for K+. Ba2+potently inhibited those currents in a voltage-dependent manner, with affinityk= 0.18, 0.33, 0.60, and 1.20 μM at −160, −120, −80, and −40 mV, respectively. Cs+also blocked those currents withk= 20, 48, 253, and 1,856 μM at −160, −120, −80, and −40 mV, respectively. In the presence of 1 mM ouabain, increasing extracellular K+concentration from 5 to 10 mM hyperpolarized endothelial membrane potential by 15 mV and raised endothelial [Ca2+]cyt. Both the K+-induced membrane hyperpolarization and the [Ca2+]cytelevation were reversed by Ba2+. Immunochemical staining verified that both pericytes and endothelial cells of DVR express KIR2.1, KIR2.2, and KIR2.3 subunits. We conclude that strong, inwardly rectifying KIR2.x isoforms are expressed in DVR and mediate K+-induced hyperpolarization of the endothelium.
