GW29-e1771 Effects of Novel Functional Buffering System in Artery Remodeling induced by Hemodynamic Changes of the Cardiovascular System
GW29-e1771 Effects of Novel Functional Buffering System in Artery Remodeling induced by Hemodynamic Changes of the Cardiovascular System
复制标题
GW29-e1771 新型功能性缓冲系统对心血管系统血流动力学变化引起的动脉重塑的影响
DOI：
10.1016/j.jacc.2018.08.210
复制
发表时间：
2018-10
影响因子：
24
通讯作者：
Xianyang Zhu
中科院分区：
文献类型：
--
作者：
Zhongchao Wang;Yue Wu;Jin Ma;Xianyang Zhu
目的高血压、动脉粥样硬化、肺动脉高压等心血管疾病的血流动力学改变所致的动脉重构(AR)在心血管系统的病理生理过程中起重要作用。然而，AR的发病机制，尤其是机械刺激诱发AR的机制尚不完全清楚，其初始因素可能是继发于血流动力学改变的跨室壁压力改变。最近的研究表明，细胞表面的缓冲系统在机械刺激对细胞的不利影响中起着保护作用，而机械刺激是导致AR的因素。以往对缓冲系统的研究主要集中在结构缓冲系统上，对功能缓冲系统的研究较少。本研究旨在探讨一种新的RhoA/BK钙复合体功能缓冲系统及其在急性呼吸窘迫综合征中的可能作用。方法采用后肢不称重(HU)大鼠作为动物模型，模拟脑循环血流动力学高血压状态和内脏循环低血压状态。采用等长肌力记录法测定RhoA和BKCa拮抗剂/激动剂对基底动脉(BA)和肠系膜三级动脉(MA)血管活性的影响。用免疫印迹、免疫共沉淀法和共聚焦显微镜观察RhoA和BKCa亚基之间的结构关系。结果显示：(1)BA型HU大鼠血管收缩功能明显增强，MA型血管收缩功能明显减弱。抑制RhoA的主要下游效应物Rho Kinase(ROCK)可显著抑制CON和HU的BA和MA的血管收缩作用，且BA对HU大鼠的抑制程度显著降低，MA的抑制程度明显增加。RhoA激动剂引起的HU大鼠血管收缩作用在BA时显著降低，而在MA时明显增强。2)RhoA-ROCK通路在BA中的表达无明显变化，但其活性在BA中显著降低，在MA中的表达和活性均显著增加。3)BKCa亚基α和β蛋白表达在BA组显著增加，而在MA组无明显变化。当我们拉下RhoA时，BA中同时检测到α和β亚单位的表达，而MA中仅检测到β亚单位的表达。HU可显著上调BK-Ca亚基的表达。当我们下调β亚基时，在BA和MA中都检测到了RhoA的表达，并且HU也显著增加了RhoA的表达。与CON相比，HU大鼠BA和MA中RhoA和BKCaα/β亚基共定位的融合荧光显著增强。结论RhoA与BKCa共定位于HU大鼠，血流动力学变化引起的机械刺激可能通过改变RhoA与BKCa的共定位而诱导小阻力动脉的功能性AR，这可能是心血管系统血流动力学改变的反向补偿。RhoA/BK钙复合体可能是对VSMC表面经典缓冲系统的补充，共同发挥保护作用，以补偿外源性应力变化对VSMC的不利刺激。
ObjectivesArtery remodeling (AR) induced by hemodynamic changes in various cardiovascular diseases including hypertension, atherosclerosis and pulmonary artery hypertension has been proved playing significant roles in the pathophysiological progress of the cardiovascular system. However, the mechanisms underlying AR, especially mechanical stimuli-induced AR are not fully understood, the initial factor of which might be transmural pressure alterations secondary to hemodynamic changes. Recent studies have demonstrated the protective role of buffering system at cell surface in the detrimental cellular effects of mechanical stimulus, which contributes to AR. Previous studies investigating buffering system were mainly focused on the structural buffering system, few studies payed attention to the functional buffering system. We intended to investigate a novel functional buffering system of RhoA/BK Ca complex and the possible role of this system in AR.MethodsThe present study adopted hindlimb unweighted (HU) rat as the animal model to simulate hemodynamically hypertensive condition in cerebral circulation and hypotensive condition in splanchnic circulation. Isometric force recording was used to determine the vasoactive capacity alterations of basilar artery (BA) and third-order mesenteric artery (MA) in the presence of RhoA and BK Ca antagonist/agonist or not. Western blot, co-immunoprecipitation (co-IP) and confocal microscopy were applied to investigate the structural relationship between RhoA and BK Ca subunits.ResultsResults showed that 1) Vasoconstriction of HU rats was significantly increased in BA and decreased in MA, respectively. Inhibition of Rho kinase (ROCK), the main downstream effector of RhoA, significantly restrained BA and MA vasoconstriction in both CON and HU, and the restrained extent of HU rats was significantly decreased in BA but increased in MA, respectively. RhoA agonist-elicited vasoconstriction of HU rats was significantly decreased in BA and increased in MA. 2) The protein expression of RhoA-ROCK pathway was not changed but their activity was significantly decreased in BA, and both the expression and activity were significantly increased in MA. 3) The protein expression of α and β subunits of BK Ca of HU rats was significantly increased in BA but not changed in MA. When we pulled down RhoA, both the expression of α and β subunits was detected in BA, but only the expression of β subunit was detected in MA. And HU significantly upregulated the expression of BK Ca subunits. When we pulled down β subunit, the expression of RhoA was detected in both BA and MA, and HU also significantly increased RhoA expression. Confocal microscopy further confirms the aforementioned results, as relative to CON, the merged fluorescence by colocolization of RhoA and BK Ca α/β subunits was significantly strengthened in both BA and MA of HU rats.ConclusionsThese results indicate that RhoA co-localizes with BK Ca, and mechanical stimuli by hemodynamic changes in HU rat may induce the functional AR of small resistant arteries through modification of co-localization between RhoA and BK Ca, which might inversely compensate altered hemodynamic conditions in cardiovascular system. RhoA/BK Ca complex may be a supplement of the classic buffering system on the surface of VSMCs, and function together in a protective way to compensate the adverse stimuli by exogenous stress changes on VSMCs.