Saleh Sohag N, Albert Anthony P, Peppiatt-Wildman C M, Large William A
Ion Channels and Cell Signalling Research Centre, Division of Basic Medical Sciences, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
J Physiol. 2008 May 15;586(10):2463-76. doi: 10.1113/jphysiol.2008.152157. Epub 2008 Mar 20.
In vascular smooth muscle, store-operated channels (SOCs) contribute to many physiological functions including vasoconstriction and cell growth and proliferation. In the present work we compared the properties of SOCs in freshly dispersed myocytes from rabbit coronary and mesenteric arteries and portal vein. Cyclopiazonic acid (CPA)-induced whole-cell SOC currents were sixfold greater at negative membrane potentials and displayed markedly different rectification properties and reversal potentials in coronary compared to mesenteric artery myocytes. Single channel studies showed that endothelin-1, CPA and the cell-permeant Ca(2+) chelator BAPTA-AM activated the same 2.6 pS SOC in coronary artery. In 1.5 mM Ca(2+) the unitary conductance of SOCs was significantly greater in coronary than in mesenteric artery. Moreover in 0 mM Ca(2+) the conductance of SOCs in coronary artery was unaltered whereas the conductance of SOCs in mesenteric artery was increased fourfold. In coronary artery SOCs were inhibited by the protein kinase C (PKC) inhibitor chelerythrine and activated by the phorbol ester phorbol 12,13-dibutyrate (PDBu), the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) and a catalytic subunit of PKC. These data infer an important role for PKC in activation of SOCs in coronary artery similar to mesenteric artery and portal vein. Anti-TRPC1 and -TRPC5 antibodies inhibited SOCs in coronary and mesenteric arteries and portal vein but anti-TRPC6 blocked SOCs only in coronary artery and anti-TRPC7 blocked SOCs only in portal vein. Immunoprecipitation showed associations between TRPC1 and TRPC5 in all preparations but between TRPC5 and TRPC6 only in coronary artery and between TRPC5 and TRPC7 only in portal vein. Finally, flufenamic acid increased SOC activity in coronary artery but inhibited SOCs in mesenteric artery and portal vein myocytes. These data provide strong evidence that vascular myocytes express diverse SOC isoforms, which are likely to be composed of different TRPC proteins and have different physiological functions.
在血管平滑肌中，储存操纵性通道（SOCs）参与多种生理功能，包括血管收缩以及细胞生长和增殖。在本研究中，我们比较了从兔冠状动脉、肠系膜动脉和门静脉新鲜分离的心肌细胞中SOCs的特性。与肠系膜动脉心肌细胞相比，环匹阿尼酸（CPA）诱导的全细胞SOC电流在负膜电位时大6倍，并且在冠状动脉中表现出明显不同的整流特性和反转电位。单通道研究表明，内皮素-1、CPA和细胞可渗透的Ca(2+)螯合剂BAPTA-AM在冠状动脉中激活相同的2.6 pS SOC。在1.5 mM Ca(2+)时，冠状动脉中SOCs的单位电导显著大于肠系膜动脉。此外，在0 mM Ca(2+)时，冠状动脉中SOCs的电导未改变，而肠系膜动脉中SOCs的电导增加了4倍。在冠状动脉中，SOCs被蛋白激酶C（PKC）抑制剂白屈菜红碱抑制，并被佛波酯佛波醇12,13 - 二丁酸酯（PDBu）、二酰基甘油类似物1 - 油酰基 - 2 - 乙酰基 - sn - 甘油（OAG）和PKC的催化亚基激活。这些数据表明PKC在冠状动脉SOCs激活中起重要作用，类似于肠系膜动脉和门静脉。抗TRPC1和 - TRPC5抗体抑制冠状动脉、肠系膜动脉和门静脉中的SOCs，但抗TRPC6仅阻断冠状动脉中的SOCs，抗TRPC7仅阻断门静脉中的SOCs。免疫沉淀显示所有制剂中TRPC1和TRPC5之间存在关联，但仅在冠状动脉中TRPC5和TRPC6之间存在关联，仅在门静脉中TRPC5和TRPC7之间存在关联。最后，氟芬那酸增加冠状动脉中SOC的活性，但抑制肠系膜动脉和门静脉心肌细胞中的SOCs。这些数据提供了强有力的证据，表明血管心肌细胞表达多种SOC亚型，它们可能由不同的TRPC蛋白组成并具有不同的生理功能。
