MECHANISMS OF ISCHEMIA/REPERFUSION LUNG INJURY

本课题将研究肺脏的发病机制。 缺血/再灌注(I/R)损伤的最终目标是 发现I/R的治疗是一个重要的临床问题。我们会 在清醒的绵羊身上使用一种新的肺I/R模型；12小时后 单侧肺缺血，再灌流与 富含蛋白质的肺淋巴流量持续增加，相容 微血管表面积增加，通透性异常 或者两者兼而有之。我们建议应用我们的方法 在其他模型中开发，以区分增加的渗透率 因为我们在I/R期间没有发现任何变化 血流动力学或肺血流的区域分布 在再灌流期间，我们提出了“无血流”现象 在肺再灌流中不会发生，并将检验这一假说 再远一点。在这种模型中会发生严重的低氧血症，并与 随着湿重/干重和双肺炎症的增加， 尽管只有单侧缺血。中性粒细胞在 在肺活检或支气管肺泡检查中测量双肺 再灌流4h后再灌洗。我们提出，中性粒细胞 对肺I/R至关重要，并将通过耗尽 I/R前循环中的中性粒细胞我们的数据显示 花生四烯酸代谢产物的浓度，包括 PGE2、6-酮-PGF1α和TxB2；我们建议确定 这些以及其他体液介质，包括PGD2，LTB4，LTC4， 血小板活化因子和肿瘤坏死因子升高 在I/R期间，脂质过氧化产物，包括 共轭双烯和丙二醛在 并提示自由基氧化剂损伤是 导致肺功能障碍。我们将检验这一假设 肺I/R的氧化成分独立于 在我们的模型中，黄嘌呤氧化酶(XO)；我们将使用抑制剂 再灌流前XO的变化及对XO的测定 缺血和再灌流期间的肺泡巨噬细胞。 此外，我们提出还原型谷胱甘肽是一种重要的 防止I/R的保护器我们将增加肺谷胱甘肽n- 在再灌流前给予乙酰半胱氨酸，并将 测定还原和氧化的谷胱甘肽作为氧化剂的标志 应激也是抗氧化剂储备的标志，在肺细胞中 I/R损伤前、中淋巴和支气管肺泡灌洗。 因为腺苷对心脏I/R有有效的预防作用 和肠道，可能是通过抑制中性粒细胞超氧化物 生产，我们将在肺再灌流前注入腺苷 调查保护措施。同样，我们将表演Pilot 报道的在其他再灌注中具有保护作用的药物的研究 适合在整个动物身上使用的模型 实例抗蛋白酶。最后，我们建议开发一个模型 绵羊肺移植，补充我们积极的临床 肺移植计划，利用在此获得的信息和 应用于肺保存。

This project will examine the mechanisms of lung ischemia/reperfusion (I/R) injury with the ultimate goal to discover therapy for I/R an important clinical problem. We will use a new model of lung I/R in awake sheep; after 12 hours of unilateral lung ischemia, reperfusion is associated with a prolonged increase in flow of protein-rich lung lymph, compatible with increased microvascular surface area, abnormal permeability or a combination of both. We propose to apply methods we developed in other models to distinguish increased permeability from surface area during I/R. Because we find no changes in hemodynamics or regional distribution of pulmonary blood flow during reperfusion, we propose that the "no-flow" phenomenon does not occur in lung reperfusion and will test this hypothesis further. Severe hypoxemia occurs in this model and is associated with increased wet/dry weights and inflammation in both lungs, despite only unilateral ischemia. Neutrophils are increased in both lungs when measured in lung biopsy or in bronchoalveolar lavage at 4 hours of reperfusion. We proposed that the neutrophil is critical to lung I/R, and will investigate this by depletion of circulating neutrophils before I/R. Our data indicated an increase in concentrations of metabolic products of arachidonate, including PGE2, 6-ketoPGF1 alpha, and TxB2; we propose to determine if these and other humoral mediators, including PGD2, LTB4, LTC4, platelet activating factor and tumor necrosis factor increase significanly during I/R. Lipid peroxidation products, including conjugated dienes and malondialdehyde, increase during reperfusion and suggest that free radical oxidant injury is contributory to the lung dysfunction. We will test the hypothesis that the oxidative component of the lung I/R is independent of xanthine oxidase (XO) in our model; we will administer inhibitors of XO before reperfusion and make measurements of XO in alveolar macrophages during both ischemia and reperfusion. Further we propose that reduced glutathione is an important protector against I/R. We will increase lung glutathione by n- acetylcysteinse administration before reperfusion, and will measure reduced and oxidized glutathione as a marker of oxidant stress as well as a marker of antioxidant reserve, in cells of lung lymph and bronchoalveolar lavage before and during I/R injury. Because adenosine provides effective prevention of I/R in heart and intestine, perhaps by inhibition of neutrophil superoxide production, we will infuse adenosine before lung reperfusion to investigate protection. Similarly, we will peform pilot investigation of agents reported to protect in other reperfusion models and which are appropriate for use in whole animals, for instance antiproteases. Finally, we propose to develop a model of lung transplantation in sheep, to complement our active clinical lung transplant program, utilizing information gained herein and applied to lung preservation.