Nobe Koji, Miyatake Mari, Sone Tomoko, Honda Kazuo
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-0555, Japan.
J Pharmacol Exp Ther. 2006 Aug;318(2):530-9. doi: 10.1124/jpet.106.105015. Epub 2006 May 12.
Vascular endothelial cells (ECs), which regulate vascular tonus, serve as a barrier at the interface of vascular tissue. It is generally believed that alteration of this barrier is correlated with diabetic complications; however, a detailed mechanism has not been elucidated. This study examined alteration of bovine arterial EC functions stimulated by a thromboxane A2 analog (9,11-dideoxy-11 alpha,9 alpha-epoxymethano prostaglandin F(2 alpha); U46619) under normal and high-glucose (HG) conditions. U46619 treatment increased EC layer permeability in a time- and dose-dependent fashion. This response initially disrupted calcium-dependent EC-to-EC connections, namely, vascular endothelial cadherin (VE-CaD). Thereafter, EC force development in association with morphological changes was detected employing a reconstituted EC fiber technique, resulting in paracellular hole formation in the EC layer. Thus, we confirmed that U46619-induced enhancement of EC layer permeability involves these sequential steps. Similar trials were performed using a concentration twice that of normal glucose (22.2 mM glucose for 48 h). This treatment significantly enhanced U46619-induced EC layer permeability; furthermore, increases in both rate of VE-CaD disruption and EC fiber contraction were evident. Inhibition of calcium-independent protein kinase C and diacylglycerol kinase indicated that the glucose-dependent increase in VE-CaD disruption was mediated by a calcium-independent mechanism. Moreover, EC contraction was regulated by a typical calcium-independent pathway associated with rho kinase and actin stress fiber. Contraction was also enhanced under HG conditions. This investigation revealed that glucose-dependent enhancement of EC layer permeability is related to increases in VE-CaD disruption and EC contraction. Increases in both parameters were mediated by alteration of a calcium-independent pathway.
血管内皮细胞（ECs）调节血管张力，在血管组织界面处起屏障作用。人们普遍认为这种屏障的改变与糖尿病并发症相关；然而，具体机制尚未阐明。本研究检测了在正常和高糖（HG）条件下，血栓素A2类似物（9,11 - 二脱氧 - 11α,9α - 环氧甲叉前列腺素F(2α)；U46619）刺激下牛动脉内皮细胞功能的改变。U46619处理以时间和剂量依赖性方式增加了内皮细胞层通透性。这种反应最初破坏了依赖钙的内皮细胞与内皮细胞连接，即血管内皮钙黏蛋白（VE - CaD）。此后，采用重组内皮细胞纤维技术检测到与形态变化相关的内皮细胞力的发展，导致内皮细胞层形成细胞旁孔。因此，我们证实U46619诱导的内皮细胞层通透性增强涉及这些连续步骤。使用正常葡萄糖浓度两倍（22.2 mM葡萄糖，处理48小时）进行了类似试验。该处理显著增强了U46619诱导的内皮细胞层通透性；此外，VE - CaD破坏速率和内皮细胞纤维收缩均明显增加。对非钙依赖性蛋白激酶C和二酰甘油激酶的抑制表明，葡萄糖依赖性的VE - CaD破坏增加是由非钙依赖性机制介导的。此外，内皮细胞收缩由与rho激酶和肌动蛋白应力纤维相关的典型非钙依赖性途径调节。在HG条件下收缩也增强。本研究表明，葡萄糖依赖性的内皮细胞层通透性增强与VE - CaD破坏增加和内皮细胞收缩有关。这两个参数的增加均由非钙依赖性途径的改变介导。
