RHEOLOGICAL DETERMINANTS OF MICROVASCULAR FUNCTION

描述(申请人提供)：这项研究的总体目标是阐明血液流变学作为微血管功能的决定因素在健康和疾病中的作用。为此，活体显微镜技术将被应用于评估血细胞特性对从真正的毛细血管到为其服务的小动脉和小静脉的血流阻力的影响程度。本研究的主要目的是阐明血流动力学切应力在缺血再灌流模型和炎症过程中影响内皮细胞糖基化的作用。在之前的研究中，这项研究表明，内皮细胞糖基化的组成可能会因炎症介质的反应而改变，并在缺血/再灌注期间发生变化。已有研究表明，由于剪切力的调节和多肽fMLP的刺激，G蛋白介导的信号转导导致糖组分脱落。为了进一步阐明这些现象的剪切相关性，现提出4个具体目标。在目标#1中，将使用针对半乳糖和葡萄糖残基的凝集素、肝素和硫酸软骨素抗体以及透明质酸结合蛋白，通过活体荧光显微镜来探索小静脉中糖萼的组成。在目标2中，将在血流和缺血持续时间的分级减少期间探索微静脉多糖含量的剪应力依赖性，并将其与通过血液稀释降低血液粘度而引起的剪应力减少进行比较。在目标#3中，将通过小动脉、毛细血管和小静脉的层次结构来确定在缺血/再灌注期间和在fMLP刺激下的糖聚糖积累和脱落的相对量。在目标#4中，将确定葡聚糖积累和脱落对真实毛细血管中流动阻力的影响。这些研究的结果将有助于深入了解血流动力学与微血管壁相互作用的作用，并有助于开发治疗缺血和炎症的治疗策略。

DESCRIPTION (provided by applicant): The overall goal of this research is to elucidate the role of blood rheology as a determinant of microvascular function in health and disease. To this end, techniques of intravital microscopy will be applied to evaluate the extent to which blood cell properties affect the resistance to blood flow in vessels ranging from the true capillaries, to the arterioles and venules which serve them. The general aim of the proposed studies is to elucidate the role that hemodynamic shear stresses play in affecting the structure of the endothelial cell glycocalyx during models of ischemia followed by reperfusion, and during inflammation. During the prior period, this research has suggested that the composition of the endothelial glycocalyx may change in response to inflammatory mediators and during ischemia/reperfusion. Glycan components have been shown to be shed in response to G-protein mediated signaling resulting from modulation of shear stresses and stimulation by the peptide fMLP. To further elucidate the shear dependency of these phenomena, 4 specific aims are now proposed. In aim #1 the composition of the glycocalyx will be explored in venules by intravital fluorescence microscopy using lectins specific for galactose and glucose residues, antibodies for heparan and chondroitin sulfate, and hyaluronan binding protein. In aim #2, the shear stress dependency of venule glycan content will be explored during graded reductions in flow and duration of ischemia, and compared to reductions in shear stress incurred by reducing blood viscosity using hemodilution. In aim #3, the relative amounts of glycan accumulation and shedding during ischemia/reperfusion and with fMLP stimulation will be determined throughout the hierarchy of arterioles, capillaries and venules. In aim #4, the effect of glycan accumulation and shedding on the resistance to flow in the true capillaries will be determined. The results of these studies will provide insight into the role of hemodynamic interactions with the microvessel wall and aid development of therapeutic strategies to treat ischemia and inflammation.