Differences in STIM1 and TRPC expression in proximal and distal pulmonary arterial smooth muscle are associated with differences in Ca2+ responses to hypoxia
Differences in STIM1 and TRPC expression in proximal and distal pulmonary arterial smooth muscle are associated with differences in Ca2+ responses to hypoxia
复制标题
DOI：
10.1152/ajplung.00058.2008
复制
发表时间：
2008-07-01
影响因子：
4.9
通讯作者：
Sylvester, J. T.
中科院分区：
文献类型：
--
作者：
Lu, Wenju;Wang, Jian;Sylvester, J. T.
肺动脉平滑肌细胞（PASMC）中钙池操纵的钙通道（SOCC）是引起低血压性肺血管收缩（HPV）的重要机制之一。SOCC可能由典型瞬时受体电位（TRPC）蛋白组成，并由基质相互作用分子1（STIM 1）激活。为了评估远端PA中HPV更高的可能性，因为远端PASMC中钙池操作的Ca 2+内流（SOCE）更高，我们使用荧光显微镜和Ca 2+敏感染料Fura 2测量了PASMC原代培养物中的细胞内Ca 2+浓度（[Ca 2 +]（i））和SOCE。缺氧（4%O-2）和KCl（60 mM）均增加[Ca 2 +]（i）。反应缺氧，但不是氯化钾，更大的远端细胞。我们测量了SOCE在PASMC灌注无钙的解决方案，含有cyclopiazonic酸消耗Ca 2+存储在肌浆网和硝苯地平，以防止Ca 2+进入通过L型电压操作的Ca 2+通道。在这些条件下，远端PASMC中细胞外Ca 2+恢复引起的[Ca 2 +]（i）增加和Mn 2+引起的fura 2荧光降低更大，表明SOCE更大。此外，缺氧引起的SOCE的增加在远端细胞中也更大。PASMC和新鲜分离的去内皮化PA组织的实时定量聚合酶链反应分析显示STIM 1和7种已知TRPC亚型中的5种（TRPC 1> TRPC 6> TRPC 4>> TRPC 3近似于TRPC 5）表达。对于蛋白质（通过蛋白质印迹法测量）和mRNA，STIM 1、TRPC 1、TRPC 6和TRPC 4的表达在远端比近端PASMC和PA更大。这些结果为SOCE在HPV中的重要性提供了进一步的支持，并表明HPV在远端PA中的作用大于近端PA，因为远端PASMC中SOCC的数量和激活会产生[Ca 2 +]（i）的更大增加。
Hypoxic pulmonary vasoconstriction (HPV) requires Ca2+ influx through store-operated Ca2+ channels (SOCC) in pulmonary arterial smooth muscle cells (PASMC) and is greater in distal than proximal pulmonary arteries (PA). SOCC may be composed of canonical transient receptor potential (TRPC) proteins and activated by stromal interacting molecule 1 (STIM1). To assess the possibility that HPV is greater in distal PA because store-operated Ca2+ entry (SOCE) is greater in distal PASMC, we measured intracellular Ca2+ concentration ([Ca2+](i)) and SOCE in primary cultures of PASMC using fluorescent microscopy and the Ca2+- sensitive dye fura 2. Both hypoxia (4% O-2) and KCl (60 mM) increased [Ca2+](i). Responses to hypoxia, but not KCl, were greater in distal cells. We measured SOCE in PASMC perfused with Ca2+-free solutions containing cyclopiazonic acid to deplete Ca2+ stores in sarcoplasmic reticulum and nifedipine to prevent Ca2+ entry through L-type voltage-operated Ca2+ channels. Under these conditions, the increase in [Ca2+](i) caused by restoration of extracellular Ca2+ and the decrease in fura 2 fluorescence caused by Mn2+ were greater in distal PASMC, indicating greater SOCE. Moreover, the increase in SOCE caused by hypoxia was also greater in distal cells. Real-time quantitative polymerase chain reaction analysis of PASMC and freshly isolated deendothelialized PA tissue demonstrated expression of STIM1 and five of seven known TRPC isoforms (TRPC1 > TRPC6 > TRPC4 >> TRPC3 approximate to TRPC5). For both protein, as measured by Western blotting, and mRNA, expression of STIM1, TRPC1, TRPC6, and TRPC4 was greater in distal than proximal PASMC and PA. These results provide further support for the importance of SOCE in HPV and suggest that HPV is greater in distal than proximal PA because greater numbers and activation of SOCC in distal PASMC generate bigger increases in [Ca2+](i).