SKELETAL MUSCLE EDEMA FOLLOWING ISCHEMIS--REPERFUSION

描述：急性缺血后再灌注可导致 骨骼肌间质和细胞内水肿 四肢 如果严重的话，水肿会导致压缩性减少， 组织灌注和肢体丧失。 的机制 与局部缺血和再灌注相关的初始短暂水肿发展 导致严重持续的压迫性水肿 这 该提案旨在检验这一假设，即嗜中性粒细胞介导的 骨骼肌中透明质酸的降解导致 白蛋白的对流运输在结肠内， 白蛋白的血管外洗脱。 聚合的破坏 透明质酸减少了蛋白质运动的水合途径， 尽管由于水的存在， 水肿 用于评估该假设的体内模型将是 麻醉家兔止血带缺血后，其中结前淋巴 可以收集小腿骨骼肌的引流物。 将通过测量细胞内的 透明质酸流量和淋巴大小的变化，因为淋巴引流是 透明质酸代谢的主要成分。 附加测量 将获得骨骼肌中透明质酸大小的变化 从小腿上取的样本 组织髓过氧化物酶的测量 活性将用于确定嗜中性粒细胞的存在。 的 缺血时间长短、细胞凋亡、细胞凋亡和细胞凋亡之间的时间关系 肌红蛋白的释放，以及透明质酸降解的程度将是 仔细评估，因为肌红蛋白可能提供了一个主要来源， 透明质酸降解所需的细胞外铁。 程度 间质性水肿，根据血管外变化估计 Cr-EDTA的分布空间和天然白蛋白的质量将为 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 在静脉压升高期间，通过减去 从淋巴清除中清除血管外摄取。 的 透明质酸降解对间质和淋巴白蛋白影响 将使用局部动脉内输注 睾丸透明质酸酶 血管外冲洗的测量 透明质酸酶预处理后的白蛋白将与 缺血再灌注后。 透明质酸酶的影响 预处理对白蛋白间质对流转运的影响将是 通过比较标记白蛋白平衡的速率， 血浆、组织和淋巴液。 在体外条件下，肌红蛋白 与游离铁相比， 由激活的多形核白细胞引起。 此外，联合 透明质酸和胶原蛋白对超氧化物歧化酶产生影响 将测量活化的中性粒细胞，以确定 在淋巴结中的嗜中性粒细胞反应由于存在 细胞外基质中的这些物质。 额外的体内和体内 体外研究将确定脂溶性抗氧化剂是否更 比小的水溶性抗氧化剂或铁螯合剂更有效， 防止透明质酸降解并增强时间依赖性， 缺血-再灌注后白蛋白的血管外洗脱。 等 实验将提供关于潜在的有益效果的见解， 肢体缺血和再灌注后这些药物的作用。

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.