DYNAMICS OF FLOW-DEPENDENT ARTERIAL PERMEABILITY

描述(申请人提供)：这项研究的总体目标是了解体内血流动力学应激如何影响动脉壁对大分子的摄取以及伴随的血管炎症反应。由于大分子转运和炎症在动脉粥样硬化的发生和发展中的重要性，促使人们对其产生兴趣。这项研究的一个主要假设是，血流动力学应力的变化对血管内皮细胞功能有重要影响。这在两个方面进行了研究：内皮细胞对局部剪应力的昼夜变化的适应性反应，以及细胞对剪应力波形的谐波含量的敏感性。假设适应性反应和慢性暴露于高次谐波的剪切波均与内皮屏障功能降低和炎性介质的表达有关。 该研究计划包括两个系列的动物实验，以及在层流室内培养内皮细胞的研究。在基线实验中，将用伊文思蓝-白蛋白络合物照相密度法测量猪冠状动脉(CA)和髂外动脉(EIA)大分子通透性的空间变化。CA中的渗透率分布将根据同一血管中的壁剪切应力测量结果逐个地点进行关联；后者将通过计算区域中的流动模拟获得，这些计算区域来自动脉的注塑。在分流实验中，动静脉分流会增加一个EIA中的流动应力和切应力，而另一条动脉作为对照；白蛋白摄取与增加的持续时间和幅度的相关性将被评估。在这两个系列中，固定的组织和未固定的内皮细胞将被恢复，并将测量内皮细胞的单层组织、蛋白质分布和水平以及基因表达。在基线实验中，这些数据将与局部剪切和剪切波形相关联，并将CA和EIA的响应进行比较。在分流实验中，它们将被用来识别伴随适应的分子过程。流室实验将培养的猪动脉内皮细胞暴露在复制体内流动环境的选定成分的流动中，以分离它们对体内反应的贡献。高胆固醇血症对正常血脂动物的显著反应的影响将被检验。

DESCRIPTION (provided by applicant): The overall objective of this research is to understand how hemodynamic stress in vivo affects the uptake of macromolecules by the arterial wall and the accompanying vascular inflammatory response. The interest in macromolecular transport and inflammation is prompted by their importance in the genesis and development of atherosclerosis. A primary hypothesis of this research is that vascular endothelial function is critically influenced by changes in hemodynamic stress. This is examined in two contexts: the adaptive endothelial response to diurnal variations in local shear stress, and the sensitivity of the cells to the harmonic content of the shear stress waveform. It is hypothesized that both the adaptive response and chronic exposure to shear waveforms with high harmonic content are associated with decreases in the barrier function of the endothelium and the expression of inflammatory mediators. The research plan includes two series of animal experiments, and studies of cultured endothelial cells in laminar flow chambers. In baseline experiments, the spatial variation of macromolecular permeability in the coronary (CA) and external iliac arteries (EIA) of swine will be measured using photographic densitometry of Evans Blue dye-albumin complex. The permeability distribution in the CA will be correlated on a site-by-site basis against measures of wall shear stress in the same vessel; the latter will be obtained from flow simulations in computational regions derived from injection casts of the arteries. In shunt experiments, the flow and shear stress in one EIA will be raised by arteriovenous shunting, while the other artery serves as a control; the dependence of albumin uptake on the duration and magnitude of the increase will be assessed. In both series, fixed tissue and unfixed endothelial cells will be recovered, and endothelial monolayer organization, protein distribution and levels, and gene expression will be measured. In the baseline experiments, these data will be related to local shear and shear waveform, and the responses of the CA and EIA will be compared. In the shunt experiments, they will be used to identify the molecular process accompanying adaptation. Flow chamber experiments will expose cultured porcine arterial endothelial cells to flows that replicate selected components of the in vivo flow environment, to isolate their contributions to the in vivo response. The influence of hypercholesterolemia on significant responses found in the normolipemic animals will be examined.