Endothelial KCa channels, Ca2+ signaling & arteriolar function in the brain

描述(申请人提供)：脑内(实质)小动脉中的血管内皮细胞是正常大脑功能的关键介质，既是物理屏障，也是脑内血流的调节器。血管内皮细胞(ECs)中的钙信号和钙敏感的K+通道、IK和SK以及TRPV4通道激活了将血管调节信号传递到邻近的平滑肌(SM)和沿血管内皮细胞衬里的通路。这些信号还可能与附近的星形胶质细胞和神经元进行通讯，以调节神经血管耦合(NVC)。尽管实质小动脉(PA)内皮细胞很重要，但对其对血管张力的控制或对脑内NVC的潜在影响知之甚少。为了支持该项目，我们提供了新的数据，即EC SK、IK和TRPV4通道对PA音调和皮质脑血流有深远的影响。目的1利用一种新型的内皮细胞表达钙离子生物传感器(GCaMP2)的小鼠模型，阐明内皮细胞内钙信号转导途径以及IK、SK和TRPV4通道的性质和作用。利用这些GCaMP2小鼠，我们最近发现在内皮向SM的投射中有一个定位的、稳定的IP3介导的钙信号。这种信号被称为“脉冲星”，激活共同定位的IK通道来调节血管张力。目的2研究内皮功能对动脉粥样硬化的影响，探讨钙信号、膜电位和血管内径的变化。AIM 3建立在AIMS 1和AIMS 2的基础上，探索内皮在大脑环境中的作用，使用一种基于同时测量星形细胞终末钙离子和血管反应的新方法来评估其对NVC和血流的影响。拟议的项目将为PA内皮功能和与SM的沟通提供重要的新见解。该项目应该揭示参与调节大脑血液流动的新靶点，并建议不需要通过血脑屏障的治疗剂。 与公共健康相关：大脑中排列着小血管(小动脉)的细胞(内皮)是正常大脑功能的关键介质，既是物理屏障，也是血流的调节器。内皮细胞功能障碍是血管疾病(高血压、动脉粥样硬化)的共同特征，也可能是神经疾病(阿尔茨海默氏症)的诱因。该项目将阐明大脑小动脉内皮细胞调节大脑血流的关键控制机制。

DESCRIPTION (provided by applicant): The vascular endothelium in intracerebral (parenchymal) arterioles is a critical mediator of normal cerebral function, serving as both a physical barrier and a modulator of blood flow within the brain. Ca2+ signaling and the Ca2+-sensitive K+ channels, IK and SK, and TRPV4 channels in endothelial cells (ECs) activate pathways that transmit vasoregulatory signals to adjacent smooth muscle (SM) and along the endothelial lining of blood vessels. These signals may also communicate to nearby astrocytes and neurons to modulate neurovascular coupling (NVC). Despite the importance of parenchymal arteriolar (PA) endothelium, little is known about its control of vascular tone or potential influence on NVC in the brain. To support the Project, we provide novel data that EC SK, IK and TRPV4 channels have a profound effect on PA tone and cortical cerebral blood flow. Aim 1 will elucidate the properties and roles of endothelial Ca2+ signaling modalities, and IK, SK and TRPV4 channels in PA ECs using a novel mouse model that expresses a Ca2+ biosensor (GCaMP2) in the endothelium. Exploiting these GCaMP2 mice, we have recently discovered a localized, stationary IP3- mediated Ca2+ signal in endothelial projections to the SM. This signal, termed a "pulsar", activates co-localized IK channels to modulate vascular tone. Aim 2 will determine the impact of endothelial function on the SM of PAs, exploring Ca2+ signaling, membrane potential and vascular diameter. Aim 3 builds on Aims 1 and 2 to explore the role of the endothelium in the context of the brain, evaluating its effects on NVC and blood flow using a novel approach based on simultaneous measurement of astrocytic endfoot Ca2+ and vascular responses. The proposed project will provide significant new insight into PA endothelial function and communication to SM. This project should reveal novel targets involved in modulating blood flow in the brain and suggest therapeutic agents that do not require passage through the blood brain barrier. PUBLIC HEALTH RELEVANCE: The cells (endothelial) that line the small blood vessels (arterioles) in the brain are critical mediators of normal cerebral function, serving as both a physical barrier and a modulator of blood flow. Endothelial cell dysfunction is a common feature of blood vessel diseases (hypertension, atherosclerosis) and a likely contributor to neurological disorders (Alzheimer's). This project will elucidate key control mechanisms by which endothelial cells in cerebral arterioles regulate blood flow in the brain.