Pottosin Igor I, Bonales-Alatorre Edgar, Valencia-Cruz Georgina, Mendoza-Magaña Maria Luisa, Dobrovinskaya Oxana R
Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Villa San Sebastian, 28045, Colima, Mexico.
Pflugers Arch. 2008 Sep;456(6):1037-48. doi: 10.1007/s00424-008-0481-x. Epub 2008 May 28.
In this study, we present patch-clamp characterization of the background potassium current in human lymphoma (Jurkat cells), generated by voltage-independent 16 pS channels with a high ( approximately 100-fold) K+/Na+ selectivity. Depending on the background K+ channels density, from few per cell up to approximately 1 open channel per microm2, resting membrane potential was in the range of -40 to -83 mV, approaching E (K) = -88 mV. The background K+ channels were insensitive to margotoxin (3 nM), apamine (3 nM), and clotrimazole (1 microM), high-affinity blockers of the lymphocyte Kv1.3, SKCa2, and IKCa1 channels. The current depended weakly on external pH. Arachidonic acid (20 microM) and Hg2+ (0.3-10 microM) suppressed background K+ current in Jurkat cells by 75-90%. Background K+ current was weakly sensitive to TEA+ (IC50 = 14 mM), and was efficiently suppressed by externally applied bupivacaine (IC50 = 5 microM), quinine (IC50 = 16 microM), and Ba2+ (2 mM). Our data, in particular strong inhibition by mercuric ions, suggest that background K+ currents expressed in Jurkat cells are mediated by TWIK-related spinal cord K+ (TRESK) channels belonging to the double-pore domain K+ channel family. The presence of human TRESK in the membrane protein fraction was confirmed by Western blot analysis.
在本研究中，我们展示了人类淋巴瘤（Jurkat细胞）中背景钾电流的膜片钳特性，该电流由具有高（约100倍）K⁺/Na⁺选择性的电压非依赖性16 pS通道产生。根据背景K⁺通道密度，从每个细胞少数几个到每平方微米约1个开放通道，静息膜电位在-40至-83 mV范围内，接近E(K)= -88 mV。背景K⁺通道对玛格毒素（3 nM）、蜂毒明肽（3 nM）和克霉唑（1 μM）不敏感，这些分别是淋巴细胞Kv1.3、SKCa2和IKCa1通道的高亲和力阻断剂。电流对外部pH的依赖性较弱。花生四烯酸（20 μM）和Hg²⁺（0.3 - 10 μM）可使Jurkat细胞中的背景K⁺电流抑制75 - 90%。背景K⁺电流对TEA⁺的敏感性较弱（IC50 = 14 mM），而外部施加的布比卡因（IC50 = 5 μM）、奎宁（IC50 = 16 μM）和Ba²⁺（2 mM）可有效抑制该电流。我们的数据，特别是汞离子的强烈抑制作用，表明Jurkat细胞中表达的背景K⁺电流是由属于双孔结构域K⁺通道家族的TWIK相关脊髓K⁺（TRESK）通道介导的。通过蛋白质免疫印迹分析证实了膜蛋白组分中存在人类TRESK。
