SKELETAL MUSCLE EDEMA FOLLOWING ISCHEMIS--REPERFUSION

描述：急性缺血后再灌流可导致 大鼠骨骼肌组织间质和细胞内水肿 四肢。如果严重，水肿会导致心脏受压减少。 肢体的组织灌流和丧失。这是一种机制 与缺血和再灌流相关的最初短暂性水肿发生 转化为严重和持续的压迫性水肿的情况尚不清楚。这 该提案旨在检验中性粒细胞介导的假设 骨骼肌中透明质酸的降解导致减少 白蛋白在间质内的对流输送和延长的 白蛋白在血管外的洗脱。聚合体的颠覆 透明质酸减少体内蛋白质运动的水合途径 间质，即使由于 浮肿。用于评估这一假说的体内模型将是 兔止血带缺血后结前淋巴的麻醉 可以收集小腿骨骼肌的排泄物。 透明质酸的降解率将通过测量 自淋巴引流后透明质酸流量和淋巴大小的变化 透明质酸代谢的主要成分。其他测量结果 将从骨骼肌中透明质酸大小的变化中获得 从小腿上取的样本。组织髓过氧化物酶的测定 活性将被用来确定中性粒细胞的存在。这个 脑缺血时间长短与细胞 肌红蛋白的释放，以及透明质酸的降解程度 仔细评估，因为肌红蛋白可能是 透明质酸降解所需的胞外铁。的程度 间质水肿，从血管外的变化估计 铬-EDTA和天然白蛋白的质量分布空间将为 与透明质酸大小的变化相关。的影响 缺血再灌注对时间依赖性血管外洗脱的影响 白蛋白将在静脉压升高期间通过减法进行研究。 淋巴清除对血管外摄取的清除。这个 透明质酸降解对间质和淋巴白蛋白的影响 将使用局部动脉内输注来研究运输 睾丸透明质酸酶。血管外冲洗量的测量 将透明质酸酶预处理后的白蛋白与 在缺血-再灌流后。透明质酸酶对人体的影响 白蛋白的组织间对流输送的预处理将是 通过比较标记白蛋白的平衡率和 血浆、组织和淋巴。在体外条件下，肌红蛋白将是 与游离铁相比，其催化透明质酸降解的能力 通过激活多形核白细胞。此外，合并后的 透明质酸和胶原蛋白对酵母菌产生超氧阴离子的影响 将对激活的中性粒细胞进行测量，以确定 中性粒细胞在间质中的反应被放大 细胞外基质中的这些物质。其他体内和体内 体外研究将确定脂溶抗氧化剂是否比 比小的、水溶性的抗氧化剂或铁络合剂有效 防止透明质酸降解，增强时间依赖性， 缺血再灌流后白蛋白在血管外的洗脱。是这样的 实验将提供关于潜在有益影响的洞察力 这些药物在肢体缺血和再灌流后。

DESCRIPTION: Acute ischemia followed by reperfusion can lead to both interstitial and intracellular edema in skeletal muscle of the extremities. If severe, the edema can lead to compressive decreases in tissue perfusion and loss of the limb. The mechanism by which the initial transient edema associated with ischemia and reperfusion develops into a severe and sustained compressive edema is not known. This proposal is designed to test the hypothesis that neutrophil-mediated degradation of hyaluronan in skeletal muscle leads to diminished convective transport of albumin within the interstitium and a prolonged extravascular washout of albumin. The disruption of aggregated hyaluronan reduces hydrated pathways for protein movement within the interstitium even though there is increased matrix hydration due to the edema. The in vivo model used to evaluate this hypothesis will be anesthetized rabbit following tourniquet ischemia in which prenodal lymph draining the skeletal muscles of the lower leg can be collected. Hyaluronan degradation will be determined from measurements of the change in hyaluronan flux and size of the lymph since lymph drainage is a major component in hyaluronan metabolism. Additional measurements will be obtained on the change in hyaluronan size in skeletal muscle samples taken from the lower leg. Measurements of tissue myeloperoxidase activity will be used to determine the presence of neutrophils. The temporal relationship between the length of ischemia, the cellular release of myoglobin, and the degree of hyaluronan degradation will be carefully evaluated, since myoglobin may provide a major source of the extracellular iron required for hyaluronan degradation. The degree of interstitial edema, estimated from change in the extravascular distribution space for Cr-EDTA and mass for native albumin, will be correlated to the changes in hyaluronan size. The influence of ischemia-reperfusion on the time dependent, extravascular washout of albumin will be studied during increased venous pressure by subtracting the clearance for extravascular uptake from the lymph clearance. The influence of hyaluronan degradation on interstitial and lymph albumin transport will be studied using local intra- arterial infusion of testicular hyaluronidase. Measurements of the extravascular washout of albumin following hyaluronidase pretreatment will be compared to those following ischemia-reperfusion. The influence of hyaluronidase pretreatment on interstitial convective transport for albumin will be studied by comparing the rate of labeled albumin equilibration between plasma, tissue and lymph. Under in vitro conditions, myoglobin will be compared to free iron in its ability to catalyze hyaluronan degradation by activated polymorphonuclear leukocytes. Additionally, the combined influence of hyaluronan and collagen on superoxide production by activated neutrophils will be measured in order to determine if the neutrophil response in the interstitium is amplified by the presence of these substances in the extracellular matrix. Additional in vivo and in vitro studies will determine if a lipid soluble anti-oxidant is more effective than a small, water soluble anti-oxidant or iron chelator in preventing hyaluronan degradation and enhancing the time dependent, extravascular washout of albumin following ischemia-reperfusion. Such experiments will provide insight as to the potential beneficial effects of these agents following limb ischemia and reperfusion.