Extracellular alkalinization induces endothelium-derived nitric oxide dependent relaxation in rat thoracic aorta
Extracellular alkalinization induces endothelium-derived nitric oxide dependent relaxation in rat thoracic aorta
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DOI：
10.1016/j.niox.2010.07.008
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发表时间：
2010-12-15
影响因子：
3.9
通讯作者：
Evora, P. R. B.
中科院分区：
文献类型：
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作者：
Celotto, A. C.;Capellini, V. K.;Evora, P. R. B.
目的：探讨细胞外碱化促进大鼠胸主动脉松弛的机制。方法：采用苯肾上腺素(Phe，10(-6)M)预收缩的主动脉环，测定细胞外碱化(7.4~8.5)对细胞外碱化的松弛反应。血管反应性实验在内皮完整和去内皮的环上进行，有或没有消炎痛(10(-5)M)、NG-硝基L精氨酸甲酯(L-NAME，10(-4)M)、N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide/HCl(W-7，10(-7)M)、2，5-二甲基苯并咪唑(DMB，2×10(-5)M)和甲基-B-环糊精(10(-2)M)。此外，在DMB(2×10(-5)M)存在和不存在的情况下，观察NaOH诱导的细胞外碱化(pH 8.0和8.5)对二氨基荧光素-FM-二乙酸酯(DAF-FM DA，5mU M)负载的血管内皮细胞内一氧化氮(NO)浓度的影响。结果：细胞外碱化不能引起KCl预收缩的主动脉环血管张力的改变。在Phe预收缩的环中，细胞外碱化仅引起内皮完整环的松弛，环氧合酶抑制后这种松弛得以维持，而一氧化氮合酶(NOS)、钙/钙调蛋白和Na+/钙离子的抑制则完全阻断这种松弛。结论：在大鼠胸主动脉，NaOH细胞外碱化激活了内皮细胞的NCX逆转模式，从而激活了细胞内钙离子浓度，激活了钙/钙调蛋白依赖的一氧化氮合酶。反过来，NO的释放又促进了放松。(C)2010 Elsevier Inc.保留所有权利。
Aim: To investigate the mechanism through which the extracellular alkalinization promotes relaxation in rat thoracic aorta.Methods: The relaxation response to NaOH-induced extracellular alkalinization (7.4-8.5) was measured in aortic rings pre-contracted with phenylephrine (Phe, 10(-6) M). The vascular reactivity experiments were performed in endothelium-intact and -denuded rings, in the presence or and absence of indomethacin (10(-5) M), NG-nitro-L-arginine methyl ester (L-NAME, 10(-4) M), N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide/HCl (W-7, 10(-7) M), 2,5-dimethylbenzimidazole (DMB, 2 x 10(-5) M) and methyl-B-cyclodextrin (10(-2) M). In addition, the effects of NaOH-induced extracellular alkalinization (pH 8.0 and 8.5) on the intracellular nitric oxide (NO) concentration was evaluated in isolated endothelial cells loaded with diaminofluorescein-FM diacetate (DAF-FM DA, 5 mu M), in the presence and absence of DMB (2 x 10(-5) M).Results: The extracellular alkalinization failed to induce any change in vascular tone in aortic rings pre-contracted with KCl. In rings pre-contracted with Phe, the extracellular alkalinization caused relaxation in the endothelium-intact rings only, and this relaxation was maintained after cyclooxygenase inhibition; completely abolished by the inhibition of nitric oxide synthase (NOS), Ca2+/calmodulin and Na+/Ca2+. exchanger (NCX), and partially blunted by the caveolae disassembly.Conclusions: These results suggest that, in rat thoracic aorta, that extracellular alkalinization with NaOH activates the NCX reverse mode of endothelial cells in rat thoracic aorta, thereby the intracellular Ca2+ concentration and activating the Ca2+/calmodulin-dependent NOS. In turn, NO is released promoting relaxation. (C) 2010 Elsevier Inc. All rights reserved.