RATE SENSITIVITY TO SHEAR STRESS OF VASCULAR ENDOTHELIUM

血流诱导的切应力和最近的切应力瞬变被认为是血管内皮细胞的有效调节器。这项拟议研究的总体目标是在组织器官生理学和细胞分子生物学水平上确定这两种调节刺激的作用。这项拟议的工作将检验细胞膜可能对快速和缓慢变化的剪应力做出不同反应的假设。为了在生理水平上研究这种可能性，已知的膜调节剂(胆固醇和酒精)将被加入到完整的分离小动脉的内皮细胞中，以研究它们对切应力和剪切瞬变向血管扩张的转换的影响。这些研究将对膜流动性和微循环调节器官血流的能力之间的关系具有重要的意义。其次，将结合两种成熟的技术：剪切流细胞培养和光漂白后的荧光恢复，研究剪切和剪切瞬变对细胞膜蛋白质动力学的影响。这些新颖的实验将能够量化蛋白质和脂肪在稳定和非稳定剪切过程中的扩散，以及它们在内皮细胞信号转导中的作用。这些研究将有助于理解急性血流动力学改变时器官血流调节的机制，以及动脉粥样硬化病变优先位于非稳定剪切区的原因。

Blood flow-induced shear stress and, more recently, shear stress transients have been implicated as potent modulators of vascular endothelium. The overall goal of the proposed research is to establish the roles of both of these modulating stimuli at the tissue-organ physiology and cellular-molecular biology levels. The proposed work will test the hypothesis that the cell membrane may react differently to quickly and slowly changing shear stresses. To investigate this possibility at the physiological level, known membrane-modulating agents (cholesterol and alcohol) will be incorporated into endothelial cells in intact isolated arterioles to study their effects on the transduction of shear stress and shear transients into vessel dilation. These studies will have important implications for the relationship between membrane fluidity and the ability of the microcirculation to regulate organ blood flow. Second, the effects of shear and shear transients on cell membrane protein dynamics will be investigated by combining two established techniques: cell culture subjected to shear flow and fluorescence recovery after photobleaching. Such novel experiments will enable the quantification of protein and lipid diffusion during steady and unsteady shear and their roles in endothelial cell signal transduction. These studies will aid in understanding both the mechanisms of organ blood flow regulation during acute hemodynamic alterations and why atherosclerotic lesions are localized preferentially at areas of unsteady shear.