Role of ryanodine receptor Ca2+ channels in adaptative vascular processes

心血管疾病是全世界最常见的死亡原因，高血压是主要危险因素。阻力动脉可以根据压力和流量独立调节其血管直径。Ryanodine受体（RyRs）是肌细胞肌浆网（SR）膜上的主要Ca2+释放通道，有助于收缩。血管平滑肌细胞（VSMCs）表现出三种不同的RyR亚型（RyR1, 2,3），但它们的功能在很大程度上是未知的。我们制造了他莫昔芬诱导的平滑肌细胞（SM）特异性RyR2缺陷小鼠。我们将验证VSMC RyR2s在基本Ca2+信号传导和血管压力和/或流量的适应性血管反应中发挥特定作用的假设。使用SM RyR2缺陷小鼠，我们将研究RyR2在影响血管张力的动脉平滑肌细胞局部（sparks）和全局Ca2+处理中的作用。除了cav1.2 - l型通道外，还有额外的Ca2+内流途径（如Cav3.2, TRPC6）来触发Ca2+火花。目前还不清楚这些信号成分起什么作用，以及它们如何参与触发Ca2+火花。将进行离体VSMCs的共聚焦钙成像和膜片钳电流记录、离体动脉的肌图和视频显微镜、侧支动脉募集、血流和缺血性血管重构以及血压测量。我们的研究旨在确定RyR2在介导VSMC Ca2+火花中的特定贡献，这些火花与调节肌原性张力和全身动脉适应有关，以响应压力变化，而不是流量。阐明了CaV3.2/TRPC6-RyR2轴在这些过程中的作用。我们的研究将为高血压和其他慢性血管疾病中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。在高血压等慢性血管疾病中寻找新的治疗靶点。

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.