Karkanis T, Jiao Y, Hurley B R, Li S, Pickering J G, Sims S M
Department of Physiology, The University of Western Ontario, London, Ontario, Canada.
J Cell Physiol. 2001 May;187(2):244-55. doi: 10.1002/jcp.1069.
We have previously identified a human vascular smooth muscle clone that can reversibly convert between proliferative and contractile phenotypes. Here we compared receptor-channel coupling in these cells using fura-2 to monitor Ca(2+) and patch-clamp to record currents. Histamine elevated Ca(2+) in all cells and caused contraction of cells exhibiting the contractile phenotype. The rise of Ca(2+) persisted in Ca(2+)-free solution and was abolished by thapsigargin, indicating involvement of stores. Whole cell electrophysiological recording revealed that histamine evoked transient outward K(+) current, indicating functional receptor-channel coupling. The time-course and amplitude of the histamine-activated current were similar in cells of the proliferative and contractile phenotypes. Moreover, a large conductance K(+) channel was recorded in cell-attached patches and was activated by histamine as well as the Ca(2+) ionophore A-23187, identifying it as the large conductance Ca(2+)-dependent K(+) channel. This K(+) channel showed similar characteristics and activation in both proliferative and contractile phenotypes, indicating that expression was independent of phenotype. In contrast, histamine also elicited an inward Cl(-) current in some contractile cells, suggesting differential regulation of this current depending on phenotype. These studies demonstrate the usefulness of this human vascular cell clone for studying functional plasticity of smooth muscle, while avoiding complications arising from extended times in culture.
我们之前鉴定出一种人类血管平滑肌克隆，它能够在增殖表型和收缩表型之间可逆转换。在此，我们使用fura-2监测细胞内钙离子浓度（Ca(2+)）并采用膜片钳记录电流，比较了这些细胞中的受体-通道偶联情况。组胺使所有细胞内的Ca(2+)升高，并引起具有收缩表型的细胞发生收缩。Ca(2+)的升高在无钙溶液中持续存在，并被毒胡萝卜素消除，表明涉及钙库。全细胞膜片钳记录显示，组胺诱发瞬时外向钾离子电流，表明存在功能性受体-通道偶联。组胺激活电流的时间进程和幅度在增殖表型和收缩表型的细胞中相似。此外，在细胞贴附式膜片中记录到一种大电导钾离子通道，它可被组胺以及钙离子载体A-23187激活，确定其为大电导钙依赖性钾离子通道。这种钾离子通道在增殖表型和收缩表型细胞中表现出相似的特性和激活情况，表明其表达与表型无关。相反，组胺在一些收缩性细胞中还引发内向氯离子电流，提示该电流的调节存在表型差异。这些研究证明了这种人类血管细胞克隆在研究平滑肌功能可塑性方面的有用性，同时避免了因长时间培养带来的复杂问题。
