NEW APPROACH TO ENDOTHELIAL CLEFT STRUCTURE

我们提出了一个新的假说来解释在单独灌流的溶质和水交换的调节 通过施加到内皮细胞糖萼和内皮细胞处的剪切应力， 膜的总的假设是，内皮细胞的三维有序特性 使其能够作为血浆蛋白的主要分子筛的糖萼也决定了其 作为剪切应力传感器来调节内皮屏障渗透性。目标1是测量小 当施加剪切力时，单个灌注微血管中的溶质和大溶质渗透系数 应力是变化的，而糖萼的结构得以保持。经血管水通量和有效 将测量血浆蛋白的渗透压。具体的假设是一个完整的糖萼 作为机械换能器和主要分子筛将增加小溶质渗透性， 对大分子的渗透性和选择性没有变化。在目的2中，糖萼的结构是 改性以降低其作为分子筛的作用，并允许剪切应力更接近于分子筛施加。 内皮表面具体的假设是，完整的糖萼通常保护剪切感应 在内皮细胞膜上的机械转换器，调节水和所有 溶质。目的3是在具有和不具有完整的微血管的情况下，在非常低的剪切下长时间灌注微血管。 糖萼具体的假设是，需要持续的剪切应力来维持内皮细胞的生长。 表型，其中剪切应力的急剧变化引起小溶质渗透性的快速调节， 水没有变化，溶质渗透性大。将指导实验设计和解释 通过我们目前的水和溶质通过糖萼和内皮细胞间裂隙转运的模型， 从糖萼到皮层细胞骨架的力传递的新模型。将合并的 微灌注，生物物理，超微结构和建模方法将提供新的理解， 在正常微血管中通过剪切应力调节渗透性，并可能导致改善营养的策略。 递送和增强损伤或手术后的组织恢复。我们的实验评估了 调节水、溶质、白细胞和红细胞的内皮糖萼的机械性质 在内皮细胞表面的通量。

We propose a new hypothesis to explain the regulation of solute and water exchange in individually perfused mammalian microvessels by shear stress applied to the endothelial cell glycocalyx and at the endothelial cell membrane. The overall hypothesis is that the three-dimensional ordered properties of the endothelial glycocalyx which enable it to function as the primary molecular sieve for plasma proteins also determine its function as a shear stress sensor to regulate endothelial barrier permeability. Aim 1 is to measure both small solute and large solute permeability coefficients in individually perfused microvessels when applied shear stress is varied, and the structure of the glycocalyx is maintained. Transvascular water flux and effective osmotic pressures of plasma proteins will be measured. The specific hypothesis is that an intact glycocalyx acting as a mechanotransducer and the principal molecular sieve will increase small solute permeability with no change in the permeability and selectivity to large molecules. In Aim 2 the structure of the glycocalyx is modified to reduce its action as a molecular sieve and to allow shear stress to be applied closer to the endothelial surface. The specific hypothesis is that the intact glycocalyx normally protects shear-sensing mechanotransducers at the endothelial cell membrane that regulate a common pathway for water and all solutes. Aim 3 is to perfuse microvessels for long periods at very low shear with and without an intact glycocalyx. The specific hypothesis is that continuous shear stress is required to maintain an endothelial phenotype in which an acute change in shear stress causes rapid regulation of small solute permeability, with no change in water and large solute permeability. Experimental design and interpretation will be guided by our current model of water and solute transport through the glycocalyx and inter-endothelial cleft and by a new model of force transduction from the glycocalyx to the cortical cytoskeleton. The combined microperfusion, biophysical, ultrastructural, and modeling approaches will provide new understanding of the permeability regulation by shear stress in normal microvessels and may lead to strategies to improve nutrient delivery and enhance tissue recovery after injury or surgery. Our experiments evaluate the common mechanical properties of the endothelial glycocalyx that modulate water, solute, leukocyte, and red cell fluxes at the endothelial cell surface.