Arachidonic acid-induced dilation in human coronary arterioles: convergence of signaling mechanisms on endothelial TRPV4-mediated Ca2+ entry.
Arachidonic acid-induced dilation in human coronary arterioles: convergence of signaling mechanisms on endothelial TRPV4-mediated Ca2+ entry.
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DOI：
10.1161/jaha.113.000080
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发表时间：
2013-04-25
影响因子：
5.4
通讯作者：
Zhang DX
中科院分区：
文献类型：
--
作者：
Zheng X;Zinkevich NS;Gebremedhin D;Gauthier KM;Nishijima Y;Fang J;Wilcox DA;Campbell WB;Gutterman DD;Zhang DX
花生四烯酸（AA）和/或其酶代谢产物是重要的脂质介质，有助于内皮源性超极化因子（EDHF）介导的多个血管床（包括人冠状小动脉（HCA））扩张。然而，这些脂质介质在内皮细胞（EC）中的作用机制仍不完全确定。在这项研究中，我们研究了瞬时受体电位香草酸4（TRPV 4）通道在AA诱导的内皮细胞Ca 2+反应和HCA扩张中的作用。AA在分离的HCA中诱导浓度依赖性扩张。TRPV 4拮抗剂RN-1734和内皮细胞Ca 2+激活的K+通道的抑制在很大程度上消除了扩张。在天然和TRPV 4过表达的人冠状动脉EC（HCAEC）中，AA增加细胞内Ca 2+浓度（[Ca 2 +]i），这是由TRPV 4依赖性Ca 2+内流介导的。细胞色素P450（CYP）抑制剂可抑制AA诱导的[Ca 2 +]i升高。令人惊讶的是，AA的代谢产物环氧二十碳三烯酸（EET）是TRPV 4的弱得多的激活剂，并且EET抑制剂不影响HCAEC中的EET产生。除了对[Ca 2 +]i的影响外，AA还诱导内皮细胞超极化，并且这种作用是通过TRPV 4进入Ca 2+所必需的。蛋白激酶A抑制剂PKI也可抑制AA诱导和TRPV 4介导的Ca 2+内流。TRPV 4表现出基础水平的磷酸化，其被PKI抑制。膜片钳研究表明，AA激活了HCAEC细胞贴附和由内而外的膜片中的TRPV 4单通道电流。AA通过一种新的机制扩张HCA，该机制涉及内皮TRPV 4通道依赖性Ca 2+内流，需要内皮超极化、PKA介导的TRPV 4基础磷酸化和AA直接激活TRPV 4通道。
Arachidonic acid (AA) and/or its enzymatic metabolites are important lipid mediators contributing to endothelium‐derived hyperpolarizing factor (EDHF)–mediated dilation in multiple vascular beds, including human coronary arterioles (HCAs). However, the mechanisms of action of these lipid mediators in endothelial cells (ECs) remain incompletely defined. In this study, we investigated the role of the transient receptor potential vanilloid 4 (TRPV4) channel in AA‐induced endothelial Ca2+ response and dilation of HCAs. AA induced concentration‐dependent dilation in isolated HCAs. The dilation was largely abolished by the TRPV4 antagonist RN‐1734 and by inhibition of endothelial Ca2+‐activated K+ channels. In native and TRPV4‐overexpressing human coronary artery ECs (HCAECs), AA increased intracellular Ca2+ concentration ([Ca2+]i), which was mediated by TRPV4‐dependent Ca2+ entry. The AA‐induced [Ca2+]i increase was inhibited by cytochrome P450 (CYP) inhibitors. Surprisingly, the CYP metabolites of AA, epoxyeicosatrienoic acids (EETs), were much less potent activators of TRPV4, and CYP inhibitors did not affect EET production in HCAECs. Apart from its effect on [Ca2+]i, AA induced endothelial hyperpolarization, and this effect was required for Ca2+ entry through TRPV4. AA‐induced and TRPV4‐mediated Ca2+ entry was also inhibited by the protein kinase A inhibitor PKI. TRPV4 exhibited a basal level of phosphorylation, which was inhibited by PKI. Patch‐clamp studies indicated that AA activated TRPV4 single‐channel currents in cell‐attached and inside‐out patches of HCAECs. AA dilates HCAs through a novel mechanism involving endothelial TRPV4 channel‐dependent Ca2+ entry that requires endothelial hyperpolarization, PKA‐mediated basal phosphorylation of TRPV4, and direct activation of TRPV4 channels by AA.