Macromolecular Structure of Arterial Walls

动脉壁是一个复杂的大分子结构。这些结构的主要元素之一是支架，它提供了强度和灵活性来执行手头的任务，或者在动脉压力下保持血管中的血液，或者通过冠状动脉瓣膜的功能维持压力。在过去的几年里，这些大分子的实际微观结构和组成可以影响不同疾病状态的进展，最明显的是动脉粥样硬化和瓣膜钙化。为了更好地理解这一过程，我们已经开始研究动脉血管床中大分子的精细结构，使用一种新的光学成像技术，该技术依赖于胶原蛋白和弹性蛋白的非线性激发（NLE），在未固定的新鲜样品中提供其结构的亚微米图像，同时使用相干反斯托克斯拉曼散射（CARS）直接监测水通过壁面的渗透。这些结果表明，水渗透的主要障碍是内皮细胞的基底外侧膜。而顶膜（面向血液）对水具有高度渗透性。我们推测顶膜AQP-1是顶膜高透水性的主要来源。新的研究包括：1)在回顾我们早期工作时提出的一个问题是，是否可以在培养的血管内皮细胞上进行研究，这样可以实现更多的控制和更好的光学。我们与剑桥大学的黄博士一起探索了这种可能性，试图开发一种体外培养的血管内皮细胞制剂，使其在根尖和基底膜中适当分布蛋白质。这些研究表明，培养系统不能产生足够的不透水性来进行这些研究。2)与牛津大学的Dora博士一起，我们正在将灌注血管的研究扩展到小鼠的大脑内动脉。从临床和基础科学的角度来看，在颅骨体积受限的结构中，这些血管中的水处理特别有趣。我们发现这些小血管产生的动脉壁图像远好于我们在肠系膜动脉上的发现。我们重新建立了一只AQP-1敲除小鼠来验证我们的假设，即由于AQP-1的存在，顶膜高度透水。在新建立的大脑上动脉模型中，我们发现正常小鼠和敲除小鼠没有差异，这表明AQP-1不是导致顶膜高透水性的主要因素。我们现在正在探索其他可能性。

The arterial wall is a complex macromolecular structure. One of the major elements of these structures is the scaffold that provides the strength and flexibility to perform the task in hand either retaining the blood in vessels against the arterial pressure or maintaining pressure via the function of coronary valves. In the last several years it has become apparent that the actual microstructure and composition of these macromolecules could influence the progress of different disease states most notably atherosclerosis and valve calcification. To gain a better understanding of this process, we have embarked on studies to understand the fine structure of the macromolecules in arterial vascular bed using a novel optical imaging technique that relies on the non-linear excitation (NLE) of collagen and elastin to provide sub-micron images of their structure in unfixed fresh samples together with direct monitoring of water permeation through the wall using Coherent anti-Stokes Raman Scattering(CARS). These results were published demonstrating that the major barrier to water permeation was the basolateral membrane of the endothelial cells. While the apical membrane (facing the blood) was highly permeable to water. We hypothesized that apical membrane AQP-1 was the major source of high water permeability in the apical membrane. New studies included: 1) One question raised in the review of our earlier work was whether this could be studied on vascular endothelial cells in culture where more control and better optics could be realized. We explored this possibility with Dr. Huang at Cambridge University to attempt to develop an in vitro cultured vascular endothelial cell preparation with appropriate distribution of proteins in the apical and basolateral membranes. These studies revealed that the culture systems do not generate adequate water impermeability to conduct these studies. 2) Together with Dr. Dora at the University of Oxford we are expanding our studies on perfused vessels to include the mouse internal cerebral arteries. The water handling in these vessels in the volume restricted structure of the skull was particularly interesting from both a clinical and basic sciences perspective. We have found that these smaller vessels generate far superior images of the artery wall and confirmed our findings in the rate mesenteric arteries. We re-established a AQP-1 knockout mouse to test our hypothesis that the apical membrane is highly permeable to water due the presence of AQP-1. Using the newly developed superior cerebral artery model we found no difference in the control and knockout mouse suggesting that AQP-1 is not the major element in the high water permeability of the apical membrane. We are now exploring other possibilities.