RHEOLOGICAL DETERMINANTS OF MICROVASCULAR FUNCTION

描述（由申请人提供）：本研究的总体目标是阐明血液流变学在健康和疾病中作为微血管功能决定因素的作用。为此，将应用活体显微技术来评估血细胞特性对血管血流阻力的影响程度，从真正的毛细血管到为毛细血管服务的小动脉和小静脉。所提出的研究的总体目的是阐明血流动力学剪切应力在缺血再灌注模型和炎症期间影响内皮细胞糖萼结构的作用。在之前的研究中，本研究表明内皮糖萼的组成可能会在炎症介质和缺血/再灌注过程中发生变化。多糖成分已被证明在g蛋白介导的信号传导反应中脱落，这是由肽fMLP对剪切应力和刺激的调节引起的。为了进一步阐明这些现象的剪切依赖性，现在提出了4个具体目标。在目标#1中，将使用半乳糖和葡萄糖残基特异性凝集素，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探索小静脉中糖花苞的组成。在目的#2中，将探讨小静脉聚糖含量在血流和缺血持续时间逐渐减少期间的剪切应力依赖性，并与使用血液稀释降低血液粘度所引起的剪切应力减少进行比较。在目的#3中，在缺血/再灌注和fMLP刺激下，多糖积累和脱落的相对量将在整个小动脉、毛细血管和小静脉的层次中确定。在目标#4中，将确定聚糖的积累和脱落对真正毛细血管中流动阻力的影响。这些研究的结果将为血液动力学与微血管壁相互作用的作用提供深入的了解，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.