ALTERED VASCULAR SMOOTH MUSCLE IN HYPERCHOLESTEROLEMIA

人们越来越清楚，血胆固醇升高 水平导致动脉壁功能的改变， 从它在动脉粥样硬化病因学中的作用。 这是 表现为动脉超敏反应和器官供血减少 饮食性高胆固醇血症期间报告的流量。 过量 胆固醇已显示改变细胞膜介导的功能， 几种细胞类型，并以这种方式可能有助于改变细胞 功能 根据这个实验室和其他实验室的数据， 提出了一个假设，即胆固醇水平升高会导致 在过量胆固醇进入细胞膜的过程中， 动脉壁细胞，从而改变膜流动性， 跨膜离子运动。 我们认为这些变化改变了 兴奋-收缩耦合，并有助于动脉 高胆固醇血症并发超敏反应。 广泛的目标 这项建议的目的是确定胆固醇 改变细胞膜，导致细胞功能异常， 动脉平滑肌细胞（SMC）和内皮细胞（EC）。 该提案反映了该实验室的长期目标， 正在研究改变膜脂成分对 动脉SMC和EC的细胞功能。 的具体目标 本研究旨在确定：1、过量胆固醇的影响 对质膜的物理状态（流动性）的影响 SMC和EC，以及2，这些膜改变对 跨膜钙、钾和钠的运动和功能 在平滑肌细胞，3，这些膜的影响， 跨膜钙、钾和钠的改变 内皮细胞的运动和功能。 两名将军和 解决这一问题的补充方法将是 采用 首先，将在体外灌注兔动脉， 胆固醇富集的细胞质膜膜的 血管将用富含胆固醇的脂质体完成。 环 这些血管的节段将用于研究平滑肌 收缩与离子通量研究平行。 其次，我们将 检查胆固醇富集对内皮细胞的影响 功能（EDRF释放）和跨膜离子运动， 兔内皮原代细胞培养物。 此外，离子通量 还将在培养的兔SMC中进行研究，以确定 跨膜离子运动的细节无法以其他方式辨别 在完整的血管节段中。 胆固醇富集的影响 通过测量膜的物理状态（流动性） 荧光各向异性将有助于确定分子机制 胆固醇的影响。 综合这些结果， 方法论方法将允许进行全面和广泛的分析 胆固醇改变动脉的分子机制 反应性 这项研究将提供新的见解， 改变膜胆固醇组成与细胞之间的相互作用 功能，并将有助于我们了解细胞的 血管舒缩不适当的潜在机制 高胆固醇血症

It is becoming increasingly clear that elevated blood cholesterol levels result in alterations in arterial wall function, quite apart from its role in the etiology of atherosclerosis. This is indicated by arterial hypersensitivity and reduced organ blood flows reported during dietary hypercholesterolemia. Excess cholesterol has been shown to alter membrane mediated functions in several cell types and in this way may contribute to altered cell function. Based on data from this and other laboratories, we have developed the hypothesis that elevated cholesterol levels result in the incorporation of excess cholesterol into membranes of the arterial wall cells, thereby altering membrane fluidity and transmembrane ion movements. We believe that these changes alter excitation-contraction coupling and contribute to the arterial hypersensitivity complicating hypercholesterolemia. The broad aim of this proposal is to determine the mechanism by which cholesterol alters cell membranes and contributes to abnormal cell function in arterial smooth muscle cells (SMC) and endothelial cells (EC). This proposal reflects the long-term goal of this laboratory which is in study the effects of altering membrane lipid composition on cell function in arterial SMC's and EC's. The specific aims of this study are to determine: 1, the effects of excess cholesterol on the physical state (fluidity) of the plasmalemma membrane of SMC and EC, and 2, the effects of these membrane alteration on transmembrane calcium, potassium and sodium movements and function in smooth muscle cells, and 3, the effects of these membrane alterations on transmembrane calcium, potassium and sodium movements and function in endothelial cells. Two general and complimentary methodological approaches to this problem will be used. First, rabbit arteries will be perfused in vitro, and cholesterol enrichment of the cellular plasmalemma membranes of the vessel will be accomplished with cholesterol rich liposomes. Ring segments of these vessels will be used to study smooth muscle contraction in parallel with ion flux studies. Secondly, we will examine the effects of cholesterol enrichment on endothelial cell function (EDRF release) and transmembrane ion movement using primary cell cultures of rabbit endothelium. In addition, ion flux studies will also be performed in cultured rabbit SMC to define the details of transmembrane ion movements not otherwise discernable in intact vessel segments. The effects of cholesterol enrichment on the physical state (fluidity) of the membranes measured by fluorescence anisotropy will help define the molecular mechanism for cholesterol's effect. Integrating the results of these methodological approaches will permit a thorough and broad analysis of the molecular mechanisms by which cholesterol alters arterial reactivity. This study will provide new insights into the interplay between altered membrane cholesterol composition and cell function and will contribute to our understanding of the cellular mechanisms underlying inappropriate vasomotion associated with hypercholesterolemia.