Role of ryanodine receptor Ca2+ channels in adaptative vascular processes

心血管疾病是全球最常见的死亡原因，高血压是主要的危险因素。阻力动脉可以通过压力和流量独立地调整其血管直径。Ryanodine受体(RyRs)是肌细胞肌浆网(SR)膜上参与收缩的主要钙释放通道。血管平滑肌细胞(VSMCs)有三种不同的RyR亚型(RyR1、2、3)，但它们的功能在很大程度上还不清楚。我们建立了他莫昔芬诱导的RyR2基因缺陷的血管平滑肌细胞(SM)特异性小鼠。我们将验证这一假设，即VSMC RyR2在基本的钙信号转导和血管对血管压力和/或血流的适应性反应中发挥特殊作用。利用SM RyR2缺陷小鼠，我们将研究RyR2在动脉平滑肌细胞影响血管张力的局部(火花)和整体钙处理中的作用。除了Cav1.2-L类通道外，还有其他钙离子内流途径(如Cav3.2、TRPC6)触发钙火花。目前尚不清楚这些信号成分扮演着什么角色，以及它们是如何参与触发钙火花的。将对分离的VSMCs进行共聚焦钙成像和膜片钳电流记录、分离动脉的肌造影术和视频显微镜、侧支动脉的补充、血流和缺血血管重构以及血压测量。我们的研究旨在确定RyR2在调节与调节肌源性张力和全身动脉适应相关的VSMC钙火花中的特定作用，以响应压力的变化，而不是流量的变化。CaV3.2/TRPC6-RyR2轴在这些过程中的作用被阐明。我们的研究将为高血压和其他慢性血管疾病期间动脉顺应性的适应机制提供新的见解，并确定新的治疗靶点。在高血压和其他慢性血管疾病期间，并确定新的治疗靶点。

Cardiovascular disease is the most common cause of death worldwide, and hypertension is the major risk factor. Resistance arteries can adapt their vessel diameter independently by pressure and by flow. Ryanodine receptors (RyRs) are major Ca2+ release channels in the sarcoplasmic reticulum (SR) membrane of myocytes contributing to contractility. Vascular smooth muscle cells (VSMCs) exhibit three different RyR isoforms (RyR1, 2, 3), but their function is largely unknown. We generated tamoxifen-inducible smooth muscle cell (SM) specific RyR2 deficient mice. We will test the hypothesis that VSMC RyR2s play a specific role in elementary Ca2+ signaling and adaptive vascular responses to vascular pressure and/or flow. Using SM RyR2 deficient mice, we will study the role of RyR2 in local (sparks) and global Ca2+ handling in arterial smooth muscle cells affecting vascular tone. Besides Cav1.2-L-type channels, there are additional Ca2+ influx pathways (e.g. Cav3.2, TRPC6) to trigger Ca2+ sparks. It is unclear what role these signal components play and how they are involved in triggering the Ca2+ sparks. Confocal calcium imaging and patch clamp current recordings on isolated VSMCs, myography and video microscopy of isolated arteries, collateral artery recruitment, flow and ischemic vascular remodeling and blood pressure measurements will be performed. Our studies are aimed to identify a specific contribution of RyR2 in mediating VSMC Ca2+ sparks relevant for regulating myogenic tone and systemic arterial adaptation in response to changes in pressure, but not flow. The role of the CaV3.2/TRPC6-RyR2 axis is clarified in these processes. Our studies will provide new insights into adaptive mechanisms of arterial compliance during hypertension and other chronic vascular diseases and identification of novel therapeutic targets. During hypertension and other chronic vascular diseases and identification of novel therapeutic targets.