TRPV4-KCa离子通道复合体在有氧运动抗老年大鼠缺血再灌注损伤保护冠脉内皮功能中的作用

Coronary artery disease (CAD) is the most common cause of death globally. Advancing age is one of the major risk factors for CAD. Endothelial dysfunction with aging may predispose older arteries to greater ischemia-reperfusion (I/R) injury. Although increasing evidence shows that exercise can provide effective protection to the endothelium against I/R injury with advancing age, the underlying mechanisms are far from clarified. TRPV4-KCa complex on endothelium plays an important role in the regulation of arterial tone. It indicates that the dysfunction of TRPV4-KCa complex may be one of the main cause of the functional change of older arteries. However, it is still not clear about the role and mechanism of TRPV4-KCa complex in the effect of exercise on the arterial function with aging. In the present study, aged rats will be given a aerobic exercise training program. By using multiple techniques, including confocal microscopy recording, patch-clamp recording, in-vivo cardiovascular function investigation, isometric tension measurement and western blotting, we will investigate the beneficial effects of aerobic exercise on the aging-induced arterial dysfunction and its effective protection to endothelium against I/R injury, and to explore the role and the potential molecular basis of TRPV4-KCa complex in this effect. This study will provide more knowledge about the cellular mechanisms underlying the exercise therapy on CAD patients with aging.

冠心病是世界上最常见的致死病因。跟年轻患者相比，老年冠心病致死率更高。因此探讨老年冠心病发病机制并寻找简单有效的防治手段成为当今研究热点。运动能增强血管内皮功能，延缓衰老，保护血管抗缺血再灌注损伤，但其作用的细胞机理还未阐明。内皮TRPV4-KCa离子通道复合体是维持血管正常张力重要调节机制，其感受血流刺激，促进钙离子内流和细胞膜超极化，诱导血管源性内皮舒张因子释放和血管舒张。TRPV4-KCa的功能异常可能是衰老导致血管功能障碍的重要原因，然而其在运动改善衰老血管功能的作用与机制未见报道。本课题拟对老年大鼠施加有氧运动训练，采用激光共聚焦荧光显微镜和膜片钳技术，结合整体心血管功能、离体血管张力测量、通道蛋白表达检测等研究手段，系统观察有氧运动对衰老动脉血管的影响以及保护衰老血管抗缺血再灌注损伤的效果，着重探讨TRPV4-KCa在其中的作用及机制，为运动防治老年冠心病细胞机理提供实验依据。

心血管疾病危险因素（例如衰老、肥胖等）引起血管功能障碍，生活方式干预（例如运动、饮食干预）可以显著上调血管内皮功能、内皮祖细胞数量和功能活性、自主神经系统功能、显著下调动脉硬化程度，从而有效改善血管功能。TRPV4和SKCa在血管内皮细胞膜形成通道复合体共同调控动脉血管内皮功能，有氧运动能逆转衰老引起的主动脉内皮TRPV4-SKCa复合体功能下调，从而改善老年大鼠主动脉舒张功能。而且，有氧运动显著增强老年大鼠冠脉平滑肌收缩功能，其中的机制可能与有氧运动下调老年大鼠冠脉平滑肌的SOCE有关。此外，运动激素Irisin可能参与运动对血管内皮功能的调控，其中包括Irisin激活血管内皮细胞膜上TRPV4通道及其介导的钙离子内流，从而引起血管内皮舒张；运动和饮食干预后外周血Irisin水平的改变与内皮祖细胞水平的改变存在正相关。最后，通过RNA-Seq技术筛选出大鼠血清中与血管衰老以及运动改善血管衰老相关的miRNA的差异表达，通过蛋白组学质谱分析筛选出冠心病患者冠脉组织相关蛋白的差异表达。我们的研究将为运动改善血管功能提供新的研究靶点，为运动改善心血管疾病的机制研究提供新的研究思路。