Acute hypoxia increases intracellular [Ca2+] in pulmonary arterial smooth muscle by enhancing capacitative Ca2+ entry
Acute hypoxia increases intracellular [Ca2+] in pulmonary arterial smooth muscle by enhancing capacitative Ca2+ entry
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DOI：
10.1152/ajplung.00448.2004
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发表时间：
2005-06-01
影响因子：
4.9
通讯作者：
Sylvester, JT
中科院分区：
文献类型：
--
作者：
Wang, J;Shimoda, LA;Sylvester, JT
肺动脉平滑肌细胞（PASMCs）内钙离子内流是导致肺血管收缩功能低下（hypoxia-pulmonary vasoconstriction，HPV）的重要机制。为了确定通过钙池操纵的钙通道（SOCCs）的容量性钙内流（CCE）是否有助于这种内流，我们使用荧光显微镜和钙敏感染料Fura-2来测量4%O-2对大鼠远端肺动脉原代培养的PASMCs细胞内[Ca 2 +] i（[Ca 2 +]i）和CCE的影响。在PASMCs中灌注无钙的Krebs Ringer碳酸氢盐溶液（KRBS），该溶液含有环匹阿尼酸以消耗肌浆网中的Ca 2+储存和硝苯地平以阻止Ca 2+通过L型电压操纵的Ca 2+通道（VOCCs）进入，缺氧显著增强细胞外[Ca ~（2+）]i的恢复引起的[Ca ~（2+）]i的增加和细胞外Mn ~（2+）淬灭fura-的速率。2荧光。这些作用，以及在用正常盐溶液灌注的PASMCs中由缺氧引起的[Ca 2 +]i增加，被SOCC拮抗剂SKF- 96365、NiCl 2和LaCl 3阻断，其浓度抑制CCE > 80%，但不改变[Ca 2 +] i对60 mM KCl的反应。与此相反，VOCC拮抗剂硝苯地平抑制[Ca 2 +]i反应缺氧只有50%的浓度，完全阻断KCl的反应。缺氧引起的[Ca ~（2+）]i升高可被无Ca ~（2+）KRBS完全逆转。LaCl 3增加基础[Ca 2 +]i在常氧，表明影响以外的抑制SOCCs。我们的研究结果表明，急性缺氧通过SOCCs增强远端PASMCs的CCE，导致去极化，二次激活VOCCs，增加[Ca 2 +]i SOCCs和CCE可能在HPV中起重要作用。
Hypoxic pulmonary vasoconstriction (HPV) requires influx of extracellular Ca2+ in pulmonary arterial smooth muscle cells (PASMCs). To determine whether capacitative Ca2+ entry (CCE) through store- operated Ca2+ channels (SOCCs) contributes to this influx, we used fluorescent microscopy and the Ca2+-sensitive dye fura-2 to measure effects of 4% O-2 on intracellular [Ca2+] ([Ca2+]i) and CCE in primary cultures of PASMCs from rat distal pulmonary arteries. In PASMCs perfused with Ca2+-free Krebs Ringer bicarbonate solution (KRBS) containing cyclopiazonic acid to deplete Ca2+ stores in sarcoplasmic reticulum and nifedipine to prevent Ca2+ entry through L-type voltage-operated Ca2+ channels (VOCCs), hypoxia markedly enhanced both the increase in [Ca2+ ]i caused by restoration of extracellular [ Ca2+] and the rate at which extracellular Mn2+ quenched fura-2 fluorescence. These effects, as well as the increased [Ca2+]i caused by hypoxia in PASMCs perfused with normal salt solutions, were blocked by the SOCC antagonists SKF- 96365, NiCl2, and LaCl3 at concentrations that inhibited CCE > 80% but did not alter [Ca2+] i responses to 60 mM KCl. In contrast, the VOCC antagonist nifedipine inhibited [Ca2+]i responses to hypoxia by only 50% at concentrations that completely blocked responses to KCl. The increased [Ca2+]i caused by hypoxia was completely reversed by perfusion with Ca2+ -free KRBS. LaCl3 increased basal [Ca2+]i during normoxia, indicating effects other than inhibition of SOCCs. Our results suggest that acute hypoxia enhances CCE through SOCCs in distal PASMCs, leading to depolarization, secondary activation of VOCCs, and increased [Ca2+]i SOCCs and CCE may play important roles in HPV.