Platoshyn Oleksandr, Remillard Carmelle V, Fantozzi Ivana, Mandegar Mehran, Sison Tiffany T, Zhang Shen, Burg Elyssa, Yuan Jason X-J
Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 92103, USA.
Am J Physiol Lung Cell Mol Physiol. 2004 Jul;287(1):L226-38. doi: 10.1152/ajplung.00438.2003. Epub 2004 Mar 26.
Electrical excitability, which plays an important role in excitation-contraction coupling in the pulmonary vasculature, is regulated by transmembrane ion flux in pulmonary artery smooth muscle cells (PASMC). This study examined the heterogeneous nature of native voltage-dependent K(+) channels in human PASMC. Both voltage-gated K(+) (K(V)) currents and Ca(2+)-activated K(+) (K(Ca)) currents were observed and characterized. In cell-attached patches of PASMC bathed in Ca(2+)-containing solutions, depolarization elicited a wide range of K(+) unitary conductances (6-290 pS). When cells were dialyzed with Ca(2+)-free and K(+)-containing solutions, depolarization elicited four components of K(V) currents in PASMC based on the kinetics of current activation and inactivation. Using RT-PCR, we detected transcripts of 1) 22 K(V) channel alpha-subunits (K(V)1.1-1.7, K(V)1.10, K(V)2.1, K(V)3.1, K(V)3.3-3.4, K(V)4.1-4.2, K(V)5.1, K(V) 6.1-6.3, K(V)9.1, K(V)9.3, K(V)10.1, and K(V)11.1), 2) three K(V) channel beta-subunits (K(V)beta 1-3), 3) four K(Ca) channel alpha-subunits (Slo-alpha 1 and SK2-SK4), and 4) four K(Ca) channel beta-subunits (K(Ca)beta 1-4). Our results show that human PASMC exhibit a variety of voltage-dependent K(+) currents with variable kinetics and conductances, which may result from various unique combinations of alpha- and beta-subunits forming the native channels. Functional expression of these channels plays a critical role in the regulation of membrane potential, cytoplasmic Ca(2+), and pulmonary vasomotor tone.
电兴奋性在肺血管系统的兴奋-收缩偶联中起重要作用，它由肺动脉平滑肌细胞（PASMC）中的跨膜离子通量调节。本研究检测了人PASMC中天然电压依赖性钾通道的异质性。观察并表征了电压门控钾（K(V)）电流和钙激活钾（K(Ca)）电流。在浸浴于含钙溶液的PASMC的细胞贴附片中，去极化引发了广泛的钾单位电导范围（6 - 290 pS）。当用无钙且含钾的溶液透析细胞时，基于电流激活和失活的动力学，去极化在PASMC中引发了四种K(V)电流成分。使用逆转录聚合酶链反应（RT-PCR），我们检测到了以下转录本：1）22种K(V)通道α亚基（K(V)1.1 - 1.7、K(V)1.10、K(V)2.1、K(V)3.1、K(V)3.3 - 3.4、K(V)4.1 - 4.2、K(V)5.1、K(V)6.1 - 6.3、K(V)9.1、K(V)9.3、K(V)10.1和K(V)11.1），2）三种K(V)通道β亚基（K(V)β1 - 3），3）四种K(Ca)通道α亚基（Slo-α1和SK2 - SK4），以及4）四种K(Ca)通道β亚基（K(Ca)β1 - 4）。我们的结果表明，人PASMC表现出多种具有可变动力学和电导的电压依赖性钾电流，这可能是由构成天然通道的α亚基和β亚基的各种独特组合所致。这些通道的功能表达在膜电位、细胞质钙和肺血管运动张力的调节中起关键作用。
