LEUKOCYTE DEFORMABILITY AND MICROVASCULAR HEMODYNAMICS

白细胞变形性和微血管血流动力学

• 批准号: 2225255
• 负责人: THOMAS C SKALAK
• 金额: $ 15.88万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2225255
• 关键词: chemoattractants; colchicine; computer simulation; cytochalasins; cytoskeleton; fluorescence microscopy; hemodynamics; histology; ischemia; laboratory rat; leukocyte adhesion molecules; light microscopy; microcirculation; micropuncture; reperfusion; vascular resistance

Ischemia is a widespread and important clinical problem manifested in diverse conditions such as hemorrhagic shock, myocardial infarction, stroke, or local tissue trauma. After reperfusion, a period of microcirculatory no-reflow often ensues, leading to deterioration of microvascular and organ function. Leukocyte adhesion and cytotoxic release are important determinants of the reperfusion injury, but the role of leukocyte deformability and attendant capillary plugging in the injury remains controversial. This study is designed to test the central hypothesis that leukocyte deformability is a significant determinant of the microvascular resistance and tissue injury under pathological conditions and that alterations in cell deformability are primarily mediated by reorganization of the cell cytoskeleton. The long-range goal is to advance understanding of the cellular mechanisms responsible for deterioration of microvascular function in low-flow organ pathology. The specific aims of the research are to measure the leukocyte deformability in vivo, the frequency and duration of leukocyte-capillary plugging, the microvascular resistance, and the extent of tissue injury during leukocyte activation by the chemoattractant peptide FMLP, and in a model of local ischemia and reperfusion in skeletal muscle, both with and without leukocyte cytoskeletal reorganization. Intravital microscopy of the rat spinotrapezius muscle will be employed to measure l) microvascular pressure gradients across single leukocyte-capillary entrance plugs using a dual micropuncture technique, 2) leukocyte plug dimensions and durations and vessel dimensions using video methods, and 3) propidium iodide uptake by non-viable skeletal muscle cells using fluorescence imaging. The measurements allow determination of the leukocyte deformability, the extent of leukocyte-capillary plugging, the microvascular resistance in arteriovenous capillary units, and the distribution of tissue injury in the same units. Using cytochalasin-D, colchicine, and pentoxifylline in conjunction with the FMLP and ischemia-reperfusion protocols, a test will be made of the hypothesis that leukocyte deformability is a significant determinant of microvascular resistance under pathological conditions, and that reorganization of cytoskeletal F-actin mediates the deformability changes. Histological reconstruction of serial sections will be used to determine the cellular composition of permanent plugs. Finally, using a hemodynamic computer network model to link the measured cell deformabilities to microvascular resistance changes, a test will made of the hypothesis that the macroscopic no-reflow response is quantitatively related to underlying changes in leukocyte cytoskeletal properties. The capability to link cellular or microcirculatory events to macroscopic organ hemodynamics provides a basis for understanding the relative roles of cell cytoskeletal reorganization and adhesion/cytotoxic release in ischemic injury, leading ultimately to improved therapeutic measures.

缺血是一个广泛而重要的临床问题 多种条件，例如出血性休克，心肌梗塞， 中风或局部组织创伤。 再灌注后，一段时间 经常发生微循环，导致 微血管和器官功能。白细胞粘附和细胞毒性释放 是再灌注损伤的重要决定因素，但 白细胞可变形性和随之而来的毛细管堵塞 仍然有争议。这项研究旨在测试中央 假说白细胞可变形性是重要的决定因素 病理下的微血管抗性和组织损伤 条件和细胞可变形性的改变主要是 通过细胞细胞骨架的重组介导。远程目标 是提高对负责的细胞机制的理解 低流量器官病理学中微血管功能的恶化。 研究的具体目的是测量白细胞 体内可变形性，白细胞毛细血管的频率和持续时间 塞，微血管抗性和组织损伤的程度 在趋化剂肽FMLP的白细胞激活期间，在A中 局部缺血的模型和骨骼肌的再灌注，包括和 没有白细胞细胞骨架重组。 插入的显微镜 将使用大鼠Spinotrapezius肌肉来测量L）微血管 使用单个白细胞毛细管入口处的压力梯度 双重微型函数技术，2）白细胞插头尺寸和持续时间 和使用视频方法的船只尺寸，以及3）碘化丙啶的摄取 使用荧光成像通过不可生存的骨骼肌细胞。 这 测量允许确定白细胞可变形性， 白细胞毛细血管堵塞的程度，微血管抗性 动毛毛细管单位，以及组织损伤的分布 相同的单元。在中使用CytoChalasin-D，秋水仙碱和五氧化丙氨酸 与FMLP和缺血 - 重新灌注方案的结合，测试将 由假设白细胞可变形性是重要的假设。 在病理条件下微血管抗性的决定因素，并且 细胞骨架F-肌动蛋白的重组介导了可变形性 更改。串行部分的组织学重建将用于 确定永久插头的细胞组成。 最后，使用一个 血液动力学网络模型链接测得的单元 微血管抵抗变化的变形，测试将由 宏观无源反应的假设是定量的 与白细胞细胞骨架特性的潜在变化有关。这 将细胞或微循环事件连接到宏观的能力 器官血流动力学为理解相对作用提供了基础 细胞细胞骨架重组和粘附/细胞毒性释放 缺血性损伤，最终导致改进的治疗措施。