自发性高血压大鼠血管平滑肌细胞中过氧化氢和超氧化物对钙的差异性调节
Differential calcium regulation by hydrogen peroxide and superoxide in vascular smooth muscle cells from spontaneously hypertensive rats.
作者信息
Tabet Fatiha, Savoia Carmine, Schiffrin Ernesto L, Touyz Rhian M
机构信息
CIHR Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, University of Montreal, Quebec, Canada.
出版信息
J Cardiovasc Pharmacol. 2004 Aug;44(2):200-8. doi: 10.1097/00005344-200408000-00009.
We investigated the role of reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2) and superoxide anion (*O2-) in the regulation of vascular smooth muscle cell (VSMC) Ca2+ concentration ([Ca2+]i) and vascular contraction and assessed whether redox-dependent Ca2+ signaling and contraction are altered in hypertension. VSMCs and mesenteric arteries from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were studied. Cells were stimulated with H2O2 (10(-4) mol/l) or LY83583 (*O2- generator, 10(-5) mol/l). [Ca2+]i and cytosolic *O2- were measured by fura-2AM and tempo-9-AC fluorescence respectively. L-type and T-type Ca2+ channels were assessed using verapamil/diltiazem and mibefradil respectively and mRNA and protein expression of these channels was assessed by real-time PCR and immunoblotting respectively. H2O2 time-dependently increased [Ca2+]i and contraction with significantly greater effects in SHR versus WKY (P < 0.001). LY83583 increased [Ca2+]i in both strains, but responses were blunted in SHR. Removal of extracellular Ca2+ abrogated [Ca2+]i responses to H2O2 and *O2-. Verapamil and diltiazem, but not mibefradil, significantly decreased H2O2 -induced [Ca2+]i responses with greater effects in SHR (P < 0.01). L-type and T-type Ca2+ channel inhibition reduced LY83583-mediated [Ca2+]i increase only in WKY cells. Both types of Ca2+ channels were expressed (mRNA and protein) in VSMCs from WKY and SHR, with greater abundance in SHR than WKY (2- to 3-fold). These results demonstrate that ROS increase vascular [Ca2+]i and contraction, primarily via extracellular Ca2+ influx. Whereas responses to H2O2 are enhanced, *O2- -mediated actions are blunted in SHR. These effects may relate to differential activation of Ca2+ channels by H2O2 and *O2-. Enhanced activation of L-type Ca2+ channels and increased Ca2+ influx by H2O2 may contribute to increased Ca2+ signaling in VSMCs from SHR.
我们研究了活性氧（ROS），特别是过氧化氢（H₂O₂）和超氧阴离子（·O₂⁻）在调节血管平滑肌细胞（VSMC）钙离子浓度（[Ca²⁺]i）和血管收缩中的作用，并评估了氧化还原依赖性Ca²⁺信号传导和收缩在高血压中是否发生改变。对来自Wistar Kyoto（WKY）大鼠和自发性高血压大鼠（SHR）的VSMC和肠系膜动脉进行了研究。用H₂O₂（10⁻⁴ mol/L）或LY83583（·O₂⁻生成剂，10⁻⁵ mol/L）刺激细胞。分别用fura-2AM和tempo-9-AC荧光法测量[Ca²⁺]i和细胞溶质·O₂⁻。分别使用维拉帕米/地尔硫䓬和米贝地尔评估L型和T型Ca²⁺通道，并分别通过实时PCR和免疫印迹法评估这些通道的mRNA和蛋白表达。H₂O₂随时间依赖性增加[Ca²⁺]i和收缩，与WKY相比，对SHR的影响显著更大（P < 0.001）。LY83583在两种品系中均增加[Ca²⁺]i，但SHR中的反应减弱。去除细胞外Ca²⁺消除了[Ca²⁺]i对H₂O₂和·O₂⁻ 的反应。维拉帕米和地尔硫䓬，但不是米贝地尔，显著降低H₂O₂诱导的[Ca²⁺]i反应，对SHR的影响更大（P < 0.01）。L型和T型Ca²⁺通道抑制仅在WKY细胞中减少LY83583介导的[Ca²⁺]i增加。两种类型的Ca²⁺通道在WKY和SHR来源的VSMC中均有表达（mRNA和蛋白），SHR中的丰度比WKY高2至3倍。这些结果表明，ROS主要通过细胞外Ca²⁺内流增加血管[Ca²⁺]i和收缩。虽然对H₂O₂的反应增强，但在SHR中·O₂⁻介导的作用减弱。这些效应可能与H₂O₂和·O₂⁻对Ca²⁺通道的不同激活有关。H₂O₂增强L型Ca²⁺通道的激活并增加Ca²⁺内流可能导致SHR来源的VSMC中Ca²⁺信号传导增加。
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