Adrenomedullin Inhibits Angiotensin II-Induced Oxidative Stress and Gene Expression in Rat Endothelial Cells
Adrenomedullin Inhibits Angiotensin II-Induced Oxidative Stress and Gene Expression in Rat Endothelial Cells
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DOI：
10.1291/hypres.28.165
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发表时间：
2005-02
影响因子：
5.4
通讯作者：
T. Yoshimoto;N. Gochou;Nozomi Fukai;Toru Sugiyama;M. Shichiri;Y. Hirata
中科院分区：
文献类型：
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作者：
T. Yoshimoto;N. Gochou;Nozomi Fukai;Toru Sugiyama;M. Shichiri;Y. Hirata
肾上腺髓质素（AM）是一种强有力的血管扩张肽，最近被认为是一种内源性抗氧化剂。然而，其在细胞水平上的潜在作用位点尚未阐明。本研究旨在探讨AM是否直接抑制血管紧张素II（Ang II）刺激的大鼠主动脉内皮细胞（EC）内活性氧（ROS）的产生和氧化还原敏感基因的表达。用二氯荧光素（DCF）荧光法测定血管紧张素Ⅱ（10-7 mol/l）可显著增加内皮细胞内ROS水平。AM以剂量依赖性方式抑制Ang II刺激的ROS产生，这种作用被超氧自由基清除剂、NAD（P）H氧化酶抑制剂和蛋白激酶A（PKA）抑制剂消除，并被细胞渗透性cAMP类似物模拟。一项实时逆转录聚合酶链反应（RT-PCR）研究表明，Ang II显著上调了一组氧化还原敏感基因（ICAM-1、VCAM-1、派-1、组织因子、MCP-1、骨桥蛋白），这些作用可被抗氧化剂N-乙酰半胱氨酸（NAC）阻断。AM通过受体介导和PKA依赖性途径，以类似的剂量依赖性方式抑制Ang II诱导的这些基因的上调，抑制程度与NAC相似。总之，本研究表明，AM通过cAMP依赖性机制有效地阻断了Ang II刺激的细胞内NAD（P）H氧化酶产生的ROS以及随后的氧化还原敏感基因表达，表明AM对促氧化刺激具有血管保护作用。
Adrenomedullin (AM), a potent vasodilator peptide, has recently been suggested to function as an endogenous antioxidant. However, its potential site of action at the cellular level has not been clarified. The present study was undertaken to investigate whether AM directly inhibits intracellular reactive oxygen species (ROS) generation and redox-sensitive gene expression stimulated by angiotensin (Ang) II in rat aortic endothelial cells (ECs). Ang II (10-7 mol/l) significantly increased intracellular ROS levels in ECs as measured by dichlorofluorescein (DCF) fluorescence. AM inhibited Ang II-stimulated ROS generation in a dose-dependent manner and this effect was abolished by a superoxide radical scavenger, NAD(P)H oxidase inhibitor, and a protein kinase A (PKA) inhibitor, and mimicked by a cell-permeable cAMP analog. A real-time reverse transcription−polymerase chain reaction (RT-PCR) study showed that Ang II significantly upregulated a set of redox-sensitive genes (ICAM-1, VCAM-1, PAI-1, tissue factor, MCP-1, osteopontin), and these effects were blocked by an antioxidant, N-acetyl cysteine (NAC). AM similarly and dose-dependently inhibited the Ang II-induced upregulation of the entire set of these genes via a receptor-mediated and PKA-dependent pathway, and the degrees of inhibition were similar to those by NAC. In conclusion, the present study demonstrated that AM potently blocked the Ang II-stimulated intracellular ROS generation from NAD(P)H oxidase and the subsequent redox-sensitive gene expression via a cAMP-dependent mechanism in ECs, suggesting that AM has vasculoprotective effects against pro-oxidant stimuli.