Ryanodine受体在肺动脉高压右心衰竭中的作用和机制研究

Right ventricle (RV) failure is a complex clinical syndrome that can be caused by pressure overload such as pulmonary arterial hypertension (PAH), and the survival of patients with PAH is closely related to RV function. While the role of intracellular Ca2+ alterations through ryanodine receptor (RyR2) in the impairment of electromechanical coupling of cardiomyocytes has been demonstrated, the impact of altered Ca2+ handling in the genesis and development of RV failure has not been investigated. In preliminary experiments we have established the presence of Ca2+ leak due to RyR2 dysfunction during RV remodeling. The central hypothesis of this application is that pathologic diastolic sarcoplasmic reticulum (SR) Ca2+ release due to abnormal modifications of RyR2 and alterations of Ca2+ handling contribute to the genesis and development of RV failure induced by PAH and correcting the dysfunction of RyR2 can delay RV remodeling. To verify this hypothesis, monocrotaline (MCT)-induced PAH rat model will be built up and divided into RV adaptive and maladaptive remodeling stages on the basis of morphometric and hemodynamic characteristics. The relationship between Ca2+ alterations with modifications of RyR2 and the RV remodeling will be analyzed by confocal microscope and molecular biology methods in vitro. We will further study the effect of RyR2 stabilizer - dantrolene on the development of RV dysfunction on the whole animal level. This study will help to interpretate the pathogenesis of RV dysfunction from the perspective of Ca2+ handling. The result will provide potential new strategies for the treatment of RV failure.

右心衰竭是肺动脉高压患者致残、致死的主要原因，是影响其预后的最重要因素。研究表明心肌细胞肌浆网上钙离子通道ryanodine受体（RyR2）功能及表达异常与细胞电－机械活动损害密切相关。我们前期工作发现肺高压右室重构过程中存在RyR2功能异常引起的舒张期钙渗漏。因此我们提出假设右室细胞RyR2参与右心衰竭的发生发展，纠正其舒张期钙渗漏可以延缓右心衰竭进展。为验证此假设拟建立野百合碱诱导肺动脉高压大鼠模型，应用超声心动图、右心导管和组织切片等手段划分大鼠右室肥厚向功能衰竭转化的不同阶段，利用激光共聚焦显微镜、免疫印记等方法探讨RyR2的钙离子调节、蛋白表达修饰与右心衰竭进展的动态演变关系和潜在分子机制，并在整体动物水平观察RyR2稳定剂丹曲林对右心衰竭发展的影响。本研究从右室细胞钙离子释放和循环的角度，探讨RyR2在肺高压右室损害过程中的作用及分子机制，为右心衰竭的诊疗提供新靶点。

肺动脉高压（PAH）是一类逐渐进展的高致死性疾病，右心衰竭是肺动脉高压患者的常见并发症，是影响其预后的最重要因素，目前尚无有效的治疗手段。本研究应用体内疾病模型与体外机制研究相结合的方法对右室心肌细胞肌浆网（SR）上钙离子通道ryanodine受体(RyR2)异常与右心衰竭的相关性进行了初步研究。首先，成功建立了野百合碱诱导PAH大鼠模型，应用超声心动图、右心导管和组织病理切片等手段划分PAH大鼠右室代偿性肥厚向失代偿衰竭进展的不同病理生理阶段。进而应用激光共聚焦显微镜钙离子成像技术和免疫印迹法证实在右心衰竭发生发展过程中，RyR2表达减低及氧化修饰显著增高，导致以舒张期钙渗漏加重为特征的功能异常。同时在整体动物水平和细胞分子水平发现RyR2稳定剂丹曲林可以通过逆转RyR2的功能异常，延缓右心衰竭的进展，降低PAH大鼠病死率。综上所述本研究从右室细胞钙离子释放的角度，探讨了RyR2在肺高压右室损害过程中的作用及分子机制，为右心衰竭的诊疗提供了新理论和新靶点。