MECHANOTRANSDUCTION BY VASCULAR SMOOTH MUSCLE

该项目的长期目标是了解结构和 血管平滑肌（VSM）机械转导的功能基础。的 VSM抵抗压力或拉伸等物理力的能力 进入动脉收缩（肌源性行为）对于维持 外周阻力和脑血流自动调节。这 应用程序已修改，以采取更系统和重点突出的 通过检查三种方法来了解肌源性行为 主要现象：肌源性张力的发展，肌源性反应性 和强制扩张我们的核心假设是大脑动脉 肌源性紧张度和反应性通过一系列互补的， 压力诱导的膜功能变化（膜电位、钙离子浓度、膜电位等） 进入），肌丝调节机制（钙敏感性）和 细胞骨架结构（肌动蛋白聚合）。目的1了解 生物物理和机械决定因素的MT发展。离散 一旦足够的压力或拉伸已经被施加， 施加在血管上，并导致细胞活化， 机制，如膜去极化和钙离子进入， 产生持续的动脉收缩或张力。我们将测试 假设肌源性张力的出现可能与 血管壁变形的特定水平，并与 阈值膜电位和/或胞质钙浓度。的 这些因子的作用，以及它们通过PKC的调节 在确定音调程度中的激活/抑制也将被 调查，因为将假设发展的语气是 与显著的肌动蛋白聚合有关。目标2：调查 通过使用完整的肌源性反应性（dphi/dP）调节因子， 和透化血管，并确定自动调节效率 MR作为不同信号转导的激活/抑制的函数 怀疑在肌原性反应中起主要作用的组分。通过使用 评价功能（反应性、膜 电位、胞浆钙浓度）和结构变化 （通过使用激光共聚焦显微镜测量G肌动蛋白荧光和F肌动蛋白， 显微镜和电子显微镜;操纵状态的 细胞骨架的药理聚合/解聚剂），我们 希望了解跨壁压和 动脉收缩（肌源性反应）。最后，突然和 这种适应性血管机制在急性炎症反应中的严重失败， 高血压（强迫扩张，高血压的主要事件） 脑病-目的3）将进行研究，以确定离子的作用， (VM钙），酶（PKC）和细胞骨架（肌动蛋白）因子在其 起源和结果。

The long-term goal of this project is to understand the structural and functional basis for vascular smooth muscle (VSM) mechanotransduction. The ability of VSM to transduce physical forces such as pressure or stretch into arterial constriction (myogenic behavior) is vital for maintaining peripheral resistance and cerebral blood flow autoregulation. This application has been revised to take a more systematic and focused approach towards understanding myogenic behavior by examining three principal phenomena: the development of myogenic tone, myogenic reactivity and forced dilation. Our central hypothesis is that cerebral artery myogenic tone and reactivity are effected via a series of complementary, pressure-induced changes in membrane function (membrane potential, calcium entry), myofilament regulatory mechanisms (calcium sensitivity) and cytoskeletal structure (actin polymerization). Aim 1 to understand the biophysical and mechanistic determinants of MT development. The discrete and measurable event occurs once a sufficient pressure or stretch has been imposed upon the vessel, and results in the activation of cellular mechanisms, such as membrane depolarization and calcium entry, that produce sustained arterial constriction or tone. We will test the hypothesis that the appearance of myogenic tone can be related to a specific level of vascular wall deformation, and is associated with a threshold membrane potential and/or cytosolic calcium concentration. The role of these factors, and of their modulation by PKC activation/inhibition in determining the extent of tone will also be investigated, as will the hypothesis that development of tone is associated with significant actin polymerization. Aim 2 is to investigate the factors that modulate myogenic reactivity (dphi/dP) by using intact and permeabilized vessels, and to define the autoregulatory efficiency of MR as a function of activation/inhibition of different signal transduction components suspected to play a major role in myogenic reactivity. By using complementary approaches to evaluate functional (reactivity, membrane potential, cytosolic calcium concentration) and structural changes (measuring G actin fluorescence and F actin by using laser confocal microscopy and electron microscopy; manipulating the state of the cytoskeleton by pharmacological polymerizing/depolymerizing agents), we hope to understand the relationship between transmural pressure and arterial constriction (myogenic reactivity). Finally, the sudden and dramatic failure of this adaptive vascular mechanism in response to acute hypertension (forced dilation, a cardinal event in hypertensive encephalopathy- AIM 3) will be investigated to determine the role of ionic (VM, calcium), enzymatic (PKC) and cytoskeletal (actin) factors in its genesis and outcome.