MECHANISMS OF NITRIC OXIDE PROTECTION IN REPERFUSION INJURY

在缺血和再灌注中观察到的许多微血管功能障碍 （L/R）的小肠已被归因于激活 粘附在毛细血管后小静脉中的多形核白细胞（PMNs） 并随后迁移到肠粘膜中。 静脉 给予某些酶抗氧化剂（例如SOD、过氧化氢酶）或 抗PMNS粘附糖蛋白的单克隆抗体 或内皮细胞减弱中性粒细胞与微静脉内皮细胞的粘附 从而减弱微血管通透性的增加 由I/R引起。 这些数据表明，白细胞和/或内皮细胞- 衍生的活性氧在促进PMNs粘附中起作用 微静脉内皮增加血管通透性。 最近 包括我们在内的几个实验室的研究表明， 一氧化氮（NO）释放化合物显著抑制这种I/R， 导致PMN粘附和微血管功能障碍。 假设：我们 提出NO减弱了中性粒细胞对缺血后心肌的粘附， 通过抑制超氧化物（O2）-和/或过氧化氢（H2 O2）- 铁催化的反应，促进合成 促炎介质和增加粘附的表达 分子。 为了验证这一假设，我们提出以下建议： 具体目标：1）表征O2之间的生化相互作用， 在不存在或存在氧化还原活性铁络合物的情况下的H2 O2和NO，2） 确定NO减弱缺氧/复氧的机制 （A/R）诱导的微静脉内皮细胞、PMN和/或 3）确定NO减弱A/R诱导的血小板凋亡的机制。 中性粒细胞与内皮细胞在血小板存在或不存在下的粘附 和4）确定NO减弱A/R诱导的细胞凋亡的机制。 内皮细胞通透性增加，无论是否存在 PMN和/或血小板。 拟议的研究将增加我们对 生物化学和细胞机制的基础， NO在肠缺血再灌注损伤中的作用 由于越来越多的人对使用NO释放化合物作为治疗药物感兴趣， 用于缺血性疾病的潜在治疗剂， 血管疾病和器官移植，从这些获得的数据 研究可能证明在设计新的治疗药物中是有用的， 治疗这些疾病。

Much of the microvascular dysfunction observed in ischemia and reperfusion (L/R) of the small intestine has been attributed to activated polymorphonuclear leukocytes (PMNs) that adhere in postcapillary venules and subsequently emigrate into the intestinal interstitium. Intravenous administration of certain enzymatic antioxidants (e.g. SOD, catalase) or monoclonal antibodies directed against the adhesion glycoproteins on PMNS or endothelial cells attenuates adhesion of PMNs to the venular endothelium and consequently attenuates the increase in microvascular permeability induced by I/R. These data suggest that leukocyte and/or endothelial cell- derived reactive oxygen species play a role in promoting adhesion of PMNs to venular endothelium which increases vascular permeability. Recent studies from several laboratories, including our own, have demonstrated that nitric oxide (NO) releasing compounds dramatically inhibit this I/R- induced PMN adhesion and microvascular dysfunction. Hypothesis: We propose that NO attenuates adhesion of PMNs to the post-ischemic endothelium by inhibiting superoxide (O2)-and/or hydrogen peroxide (H2O2)- dependent, iron-catalyzed reactions that promote the synthesis of proinflammatory mediators and increase the expression of adhesion molecules. In order to test this hypothesis, we propose the following specific aims; 1) Characterize the biochemical interactions among O2, H2O2 and NO in the absence or presence of redox-active iron complexes, 2) Determine the mechanism(s) by which NO attenuates anoxia/reoxygenation (A/R)induced oxidant production by venular endothelial cells, PMNs and /or platelets, 3) Determine the mechanisms by which NO attenuates A/R-induced PMN adhesion to endothelial cells in the absence or presence of platelets and 4) Identify the mechanisms by which NO attenuates A/R-induced increases in endothelial cell permeability int eh absence or presence of PMNs and/or platlets. The proposed studies will increase our understanding of the biochemical and cellular mechanisms that underlie the protective effects of NO in ischemia and reperfusion-induced injury in the intestine. Because of the growing interest in the use of No-releasing compounds as a potential therapeutic agents for ischemic disorders, such as occlusive vascular disease and organ transplantation, data obtained from these studies may prove useful in the design of new therapeutic agents for the treatment of these disorders.