Department of Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
J Pharmacol Exp Ther. 2011 Mar;336(3):701-8. doi: 10.1124/jpet.110.165795. Epub 2010 Dec 20.
Myoendothelial microdomain signaling via localized calcium-activated potassium channel (K(Ca)) and gap junction connexins (Cx) is critical for endothelium-dependent vasodilation in rat mesenteric artery. The present study determines the relative contribution of NO and gap junction-K(Ca) mediated microdomain signaling to endothelium-dependent vasodilation in human mesenteric artery. The hypothesis tested was that such activity is due to NO and localized K(Ca) and Cx activity. In mesenteric arteries from intestinal surgery patients, endothelium-dependent vasodilation was characterized using pressure myography with pharmacological intervention. Vessel morphology was examined using immunohistochemical and ultrastructural techniques. In vessel segments at 80 mm Hg, the intermediate (I)K(Ca) blocker 1-[(2-chlorophenyl)diphenyl-methyl]-1H-pyrazole (TRAM-34; 1 μM) inhibited bradykinin (0.1 nM-3 μM)-induced vasodilation, whereas the small (S) K(Ca) blocker apamin (50 and 100 nM) had no effect. Direct IK(Ca) activation with 1-ethyl-2-benzimidazolinone (1-EBIO; 10-300 μM) induced vasodilation, whereas cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (1-30 μM), the SK(Ca) activator, failed to dilate arteries, whereas dilation induced by 1-EBIO (10-100 μM) was blocked by TRAM-34. Bradykinin-mediated vasodilation was attenuated by putative gap junction block with carbenoxolone (100 μM), with remaining dilation blocked by N-nitro l-arginine methyl ester (100 μM) and [1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (10 μM), NO synthase and soluble guanylate cyclase blockers, respectively. In human mesenteric artery, myoendothelial gap junction and IK(Ca) activity are consistent with Cx37 and IK(Ca) microdomain expression and distribution. Data suggest that endothelium-dependent vasodilation is primarily mediated by NO, IK(Ca), and gap junction Cx37 in this vessel. Myoendothelial microdomain signaling sites are present in human mesenteric artery and are likely to contribute to endothelium-dependent vasodilation via a mechanism that is conserved between species.
肌内皮微区信号通过局部钙激活钾通道 (K(Ca)) 和缝隙连接连接蛋白 (Cx) 传递，这对大鼠肠系膜动脉中的内皮依赖性血管舒张至关重要。本研究旨在确定 NO 和缝隙连接-K(Ca)介导的微区信号对人肠系膜动脉内皮依赖性血管舒张的相对贡献。测试的假设是，这种活性归因于 NO 和局部 K(Ca) 和 Cx 活性。在来自肠道手术患者的肠系膜动脉中，使用药理学干预的压力肌描记法来描述内皮依赖性血管舒张。使用免疫组织化学和超微结构技术检查血管形态。在 80mmHg 的血管段中，中间 (I)K(Ca) 阻断剂 1-[(2-氯苯基)二苯甲基]-1H-吡唑 (TRAM-34；1μM) 抑制缓激肽 (0.1nM-3μM) 诱导的血管舒张，而小 (S) K(Ca) 阻断剂阿帕米因 (50 和 100nM) 无作用。用 1-乙基-2-苯并咪唑啉酮 (1-EBIO；10-300μM) 直接激活 IK(Ca) 诱导血管舒张，而环已基-[2-(3,5-二甲基-吡唑-1-基)-6-甲基-嘧啶-4-基]-胺 (1-30μM)，SK(Ca) 激活剂，未能扩张动脉，而 1-EBIO(10-100μM) 诱导的舒张被 TRAM-34 阻断。缓激肽介导的血管舒张被假定的缝隙连接阻断剂 carbenoxolone (100μM) 减弱，剩余的舒张被 N-硝基 L-精氨酸甲酯 (100μM) 和 [1H-[1,2,4]恶二唑-[4,3-a]喹喔啉-1-酮] (10μM) 阻断，分别为一氧化氮合酶和可溶性鸟苷酸环化酶抑制剂。在人肠系膜动脉中，肌内皮缝隙连接和 IK(Ca) 活性与 Cx37 和 IK(Ca) 微区表达和分布一致。数据表明，在该血管中，内皮依赖性血管舒张主要由 NO、IK(Ca) 和缝隙连接 Cx37 介导。肌内皮微区信号发生部位存在于人肠系膜动脉中，可能通过物种间保守的机制促进内皮依赖性血管舒张。
