mmLDL对大鼠心脑血管内皮舒张、血管平滑肌受体和血流量的作用及其机制

The minimally modified low density lipoprotein (mmLDL) is one risk factors of Atherosclerosis (AS), and its effects is still unclear. AS could induce cardiovascular diseases and cerebrovascular diseases, influence local blood flow. We have found when arteries were co-cultured with mmLDL, the function and expressions of endothelin receptors on arteries were increased. Rats tail vain injection with mmLDL was used in this research. ① Then cerebral blood flow and coronary perfusive flow were measured, respectively. Further experiments were designed to clear whether they are related to PKC, MAPK and NF-κB signal pathways. ② The coronary arteries and basilar arteries were acquired by using microscope. The techniques of using small vascular myograph system, measuring plasma level of nitric oxide, investigating the microstructure of the endothelium by electron microscope and recording membrane potential will be used to study the damage of endothelium-dependent relaxation which induced by mmLDL on coronary arteries and basilar arteries, respectively. Further study will be designed to examine whether they are related to NO, PGI2 and EDHF pathways. ③ The techniques of small vascular myograph system, RT-PCR, immunohistochemistry and western blot will be used to study the effects of mmLDL on endothelin receptors and thromboxane A2 receptors at coronary arteries and basilar arteries, respectively. Specific inhibitors were used to determine whether they are related to the PKC, MAPK and NF-κB signal pathways. The study is to investigate the effects and its mechanisms of mmLDL on blood flow, endothelium-dependent relaxation and vascular smooth muscle receptors at coronary artery and cerebral artery, and might provide new thought to prevent cardiovascular diseases and cerebrovascular diseases.

弱氧化低密度脂蛋白( mmLDL)的是动脉粥样硬化(AS)的危险因子，其作用仍不清楚。AS诱发心脑血管疾病，影响局部血流。我们发现经过器官培养，mmLDL可以增加离体动脉内皮素受体的功能和表达。本项目拟采用大鼠尾静脉注射mmLDL后考察①脑血流量、冠脉灌流量，研究其与PKC/MAPK/ NF-κB通路的关系；②显微镜下剥离血管，描记微小血管张力、测定血清NO水平、电镜下观察、测定细胞膜电位来研究mmLDL对冠状动脉、基底动脉内皮结构和舒张功能的影响，并考察是否涉及NO/PGI2/EDHF途径；③用RT-PCR，免疫组化，Western-blot等技术研究mmLDL对上述动脉内皮素受体及血栓素受体的影响，使用通路拮抗剂研究PKC / MAPK / NF-κB通路参与受体调节的激酶位点。阐明mmLDL对在体动物心脑血管血流、内皮舒张及血管平滑肌受体的作用，为心脑血管疾病的防治提供新思路。

弱弱氧化低密度脂蛋白（mmLDL）是心血管疾病的危险因子，少见mmLDL对血管平滑肌受体及在体血管内皮细胞作用的报道。我们研究mmLDL对肠系膜动脉α1受体的作用及分子机制。结果显示，mmLDL引起NA收缩量效曲线明显增强，Emax值较生理盐水（normal saline, NS）组显著增高 (P < 0.01)，α1受体拮抗剂哌唑嗪使量效曲线明显右移，mmLDL引起α1受体mRNA水平、蛋白表达较NS组显著增加，mmLDL对α2受体表达基本没有影响。腹腔注射U0126抑制了mmLDL升高IL-1β、TNF-α血清浓度及血管壁表达，抑制了mmLDL引起的NA收缩量效曲线增强，表现为Emax值较mmLDL组显著降低 (P < 0.01)，抑制了mmLDL引起的α1受体表达增高；IL-1β、TNF-α血清浓度与NA诱导最大收缩百分率成正相关；U0126抑制了mmLDL引起的血管壁pERK1/2蛋白水平增高。我们采用体外器官培养的方法考察mmLDL对大鼠冠状动脉ETA受体的影响，大鼠冠状动脉培养24 h，结果显示mmLDL时间依赖性和浓度依赖性提高了培养冠状动脉的收缩性。10 g/mL 的mmLDL与大鼠冠状动脉环共培养24h，可以引起ETA受体介导的收缩量效曲线明显左移，伴随max从对照组的100% ± 10% 显著增高到mmLDL组的228% ± 20%，同时冠状动脉环ETA受体mRNA水平和蛋白表达显著增高。使用PKC、ERK1/2或者NF-B通路的特异抑制剂与mmLDL、冠状动脉环共培养，则抑制mmLDL对冠状动脉ETA受体的作用。我们采用尾静脉注射的方法研究mmLDL对小鼠肠系膜动脉内皮的影响。结果显示尾静脉注射mmLDL损伤小鼠肠系膜动脉内皮依赖性舒张功能，显著损伤EDHF-通路，EDHF-通路活性被抑制与KCa2.3-通道、KCa3.1-通道的蛋白表达量下调有关； mmLDL显著损伤NO-通路介导的血管内皮依赖性舒张功能，而对PGI2-通路无显著影响。了解mmLDL对α1受体、ETA受体及内皮的作用可以为心血管疾病的防治提供思路。