Wong Siu Ling, Leung Fung Ping, Lau Chi Wai, Au Chak Leung, Yung Lai Ming, Yao Xiaoqiang, Chen Zhen-Yu, Vanhoutte Paul M, Gollasch Maik, Huang Yu
Institute of Vascular Medicine, Chinese University of Hong Kong, Shatin, NT, Hong Kong, China.
Circ Res. 2009 Jan 30;104(2):228-35. doi: 10.1161/CIRCRESAHA.108.179770. Epub 2008 Dec 18.
Hypertension and vascular dysfunction result in the increased release of endothelium-derived contracting factors (EDCFs), whose identity is poorly defined. We tested the hypothesis that endothelial cyclooxygenase (COX)-2 can generate EDCFs and identified the possible EDCF candidate. Changes in isometric tension of aortae of young and aged hamsters were recorded on myograph. Real-time changes in intracellular calcium concentrations (Ca(2+)) in native aortic endothelial cells were measured by imaging. Endothelium-dependent contractions were triggered by acetylcholine (ACh) after inhibition of nitric oxide production and they were abolished by COX-2 but not COX-1 inhibitors or by thromboxane-prostanoid receptor antagonists. 2-Aminoethoxydiphenyl borate (cation channel blocker) eliminated endothelium-dependent contractions and ACh-stimulated rises in endothelial cell Ca(2+). RT-PCR and Western blotting showed COX-2 expression mainly in the endothelium. Enzyme immunoassay and high-performance liquid chromatography-coupled mass spectrometry showed release of prostaglandin (PG)F(2alpha) and prostacyclin (PGI(2)) increased by ACh; only PGF(2alpha) caused contraction at relevant concentrations. COX-2 expression, ACh-stimulated contractions, and vascular sensitivity to PGF(2alpha) were augmented in aortae from aged hamsters. Human renal arteries also showed thromboxane-prostanoid receptor-mediated ACh- or PGF(2alpha)-induced contractions and COX-2-dependent release of PGF(2alpha). The present study demonstrates that PGF(2alpha), derived from COX-2, which is localized primarily in the endothelium, is the most likely EDCF underlying endothelium-dependent, thromboxane-prostanoid receptor-mediated contractions to ACh in hamster aortae. These contractions involved increases in endothelial cell Ca(2+). The results support a critical role of COX-2 in endothelium-dependent contractions in this species with an increased importance during aging and, possibly, a similar relevance in humans.
高血压和血管功能障碍导致内皮衍生收缩因子（EDCFs）释放增加，但其具体成分尚不清楚。我们检验了内皮环氧化酶（COX）-2可产生EDCFs这一假说，并确定了可能的EDCF候选物。在肌动描记器上记录年轻和老年仓鼠主动脉的等长张力变化。通过成像测量天然主动脉内皮细胞内钙离子浓度（Ca(2+)）的实时变化。在抑制一氧化氮生成后，乙酰胆碱（ACh）引发内皮依赖性收缩，而COX-2抑制剂而非COX-1抑制剂或血栓素-前列腺素受体拮抗剂可消除这种收缩。2-氨基乙氧基二苯基硼酸盐（阳离子通道阻滞剂）消除了内皮依赖性收缩以及ACh刺激引起的内皮细胞Ca(2+)升高。逆转录聚合酶链反应（RT-PCR）和蛋白质免疫印迹法显示COX-2主要在内皮中表达。酶免疫测定和高效液相色谱-质谱联用分析表明，ACh可使前列腺素（PG）F(2α)和前列环素（PGI(2)）的释放增加；只有PGF(2α)在相关浓度下引起收缩。老年仓鼠主动脉中COX-2表达、ACh刺激的收缩以及血管对PGF(2α)的敏感性增强。人肾动脉也显示血栓素-前列腺素受体介导的ACh或PGF(2α)诱导的收缩以及COX-2依赖性PGF(2α)的释放。本研究表明，主要定位于内皮的COX-2衍生的PGF(2α)是仓鼠主动脉中内皮依赖性、血栓素-前列腺素受体介导的对ACh收缩反应最可能的EDCF。这些收缩涉及内皮细胞Ca(2+)增加。结果支持COX-2在该物种内皮依赖性收缩中起关键作用，且在衰老过程中其重要性增加，在人类中可能也有类似关联。
