Liu Yang, Chen Xiao-Lan, Xu Cang-Bao, Cao Lei, Lin Jie, Chen Gen, Li Jie
Institute of Pharmacy and Pharmacology, University of South China, Hengyang, Hu'nan, China.
The First People's Hospital of Chenzhou, Xiangnan University, Chenzhou, Hu'nan, China.
Vascul Pharmacol. 2017 Sep;96-98:33-39. doi: 10.1016/j.vph.2017.08.002. Epub 2017 Aug 7.
Minimally modified low density lipoprotein (mmLDL) is a risk factor for cardiovascular disease. This study investigated the effect of mmLDL on mouse mesenteric artery endothelin type B (ET) receptors and its molecular mechanism. Mice were injected with normal saline (NS group), mmLDL in the tail vein (mmLDL group), or with both mmLDL and an intraperitoneal injection of the ERK1/2 pathway-specific inhibitor U0126 (mmLDL+U0126 group). The dose-response curve of mesenteric artery contraction induced by sarafotoxin 6c (S6c), the ET receptor agonist, was measured using a sensitive myograph system. ELISAs, RT-PCR and Western blot were used to determine the serum concentrations of mouse oxidized low density lipoprotein (oxLDL), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) as well as the expression of ET receptors, ICAM-1, VCAM-1 and phosphorylated-extracellular signal-regulated kinase 1/2 (p-ERK1/2). The S6c-induced contraction dose-response curve was significantly enhanced by mmLDL treatment and showed a significantly higher E value than in the NS group (P<0.001), and the ET receptor mRNA and protein expression in the vascular wall was significantly higher than in the NS group. The serum concentration and expression of ICAM-1 and VCAM-1 were also increased by mmLDL treatment, but intraperitoneal injection of U0126 inhibited these changes as well as the increase in p-ERK1/2 protein in the vessel wall caused by mmLDL. ICAM-1 and VCAM-1 serum concentrations were positively correlated with the S6c-induced maximum contraction of blood vessels. Increased in vivo levels of mmLDL increased the serum concentrations and expression of ICAM-1 and VCAM-1 by activating the ERK1/2 pathway, resulting in the expression of ET receptors and the enhancement of contractile function in vascular smooth muscle. Understanding the effect of mmLDL on ET receptors and its mechanism can provide ideas for cardiovascular disease prevention and treatment.
轻度修饰的低密度脂蛋白（mmLDL）是心血管疾病的一个危险因素。本研究调查了mmLDL对小鼠肠系膜动脉B型内皮素（ET）受体的影响及其分子机制。给小鼠尾静脉注射生理盐水（NS组）、mmLDL（mmLDL组），或同时注射mmLDL并腹腔注射ERK1/2通路特异性抑制剂U0126（mmLDL+U0126组）。使用灵敏的肌动描记系统测量ET受体激动剂沙拉毒素6c（S6c）诱导的肠系膜动脉收缩的剂量反应曲线。采用酶联免疫吸附测定（ELISA）、逆转录聚合酶链反应（RT-PCR）和蛋白质免疫印迹法（Western blot）测定小鼠氧化低密度脂蛋白（oxLDL）、细胞间黏附分子-1（ICAM-1）和血管细胞黏附分子-1（VCAM-1）的血清浓度，以及ET受体、ICAM-1、VCAM-1和磷酸化细胞外信号调节激酶1/2（p-ERK1/2）的表达。mmLDL处理显著增强了S6c诱导的收缩剂量反应曲线，且E值显著高于NS组（P<0.001），血管壁中ET受体mRNA和蛋白表达也显著高于NS组。mmLDL处理还增加了ICAM-1和VCAM-1的血清浓度和表达，但腹腔注射U0126抑制了这些变化以及mmLDL引起的血管壁中p-ERK1/2蛋白的增加。ICAM-1和VCAM-1血清浓度与S6c诱导的血管最大收缩呈正相关。体内mmLDL水平升高通过激活ERK1/2通路增加了ICAM-1和VCAM-1的血清浓度和表达，导致ET受体表达及血管平滑肌收缩功能增强。了解mmLDL对ET受体的影响及其机制可为心血管疾病的防治提供思路。
