Regulation of the Endothelial Cell Glycocalyx

描述（申请人提供）：近年来，内皮细胞糖萼已被证明通过调节流变学、渗透性和白细胞-内皮细胞相互作用在微血管功能中起关键作用。我们现在提出扩展这些观察的假设，即糖萼是一个动态结构，受到调节，病理生理刺激可导致其降解和解体，这将有助于增强内膜通透性，血小板粘附，加速白细胞结合和白细胞从脉管系统迁移。活体视频显微镜使我们能够跟踪微循环在刺激下的变化，微灌注使我们能够标记糖萼并选择性地治疗微循环的局部小片段。我们提出了两个实验目标，这将使糖萼在内皮细胞功能中的作用更加稳固，并将为理解糖萼在病理生理学中的作用奠定基础。

DESCRIPTION (provided by applicant): In recent years the endothelial cell glycocalyx has been shown to play a pivotal role in microvessel function by modulating rheology, permeability, and leukocyte-endothelial cell interactions. We now propose to extended those observations with the hypothesis that the glycocalyx is a dynamic structure, which is regulated and that pathophysiological stimuli can cause its degradation and disorganization, which will contribute to enhanced intimal permeability, platelet adhesion, accelerated white cell binding, and emigration of white cells from the vasculature. In vivo video microscopy allows us to follow changes in the microcirculation in response to stimuli, and microperfusion allows us to mark the glycocalyx and to selectively treat small, localized segments of the microcirculation. We propose two experimental aims which will place the role of the glycocalyx in endothelial cell function on a much firmer footing, and which will set the groundwork for an understanding of the role for the glycocalyx in pathophysiology. Specific Aim #1 - to test and explore the hypothesis that the glycocalyx is an adaptive component of the vascular wall, and that it is a key potential site for damage. The following questions will be answered to test the hypothesis. 1. Do vasoactive substances alter the glycocalyx by modifying wall shear stress? 2. Do inflammatory stimuli exert a common set of effects on the size and permeability of the glycocalyx? Specific Aim #2 - to test the hypothesis that one of the key sequences of events in response to ischemia/reperfusion is the activation of adenosine receptors and their primary and/or secondary effects on the glycocalyx. The following questions will be answered to test the hypothesis. 1. Can the effects of ischemia/reperfusion on the glycocalyx be reduced by activation of the adenosine A2A receptor? 2. Can the effects of I/R be mimicked by activation of A3 receptors? 3. Are the detrimental effects of large doses of adenosine mediated though actions on mast cells, leukocytes, or endothelial cells? The proposal is based on the use of recently developed highly potent and selective adenosine blockers, and a group of genetically engineered animals. The experiments offer the potential for understanding a new level of microvascular regulation, and for developing strategies to understand the intracellular signaling that leads to modification of the glycocalyx.