Oxidants and Nitric Oxide in Post-Ischemic Heart Injury

缺血后心脏中氧自由基的产生增加，并导致一氧化氮（NO）改变。 生产和缺血后损伤。利用电子顺磁共振（EPR）和其他技术， 直接测定缺血后心肌氧自由基和NO的产生机制。 从这些和其他最近的研究，它已被证明，氧化剂改变NO生成从一氧化氮 合成酶（NOS）。然而，氧化剂在NOS结构和功能调节中的确切作用 仍然未知。最近，已经表明，在缺血条件下，氧自由基产生 酶如黄嘌呤氧化酶（XO）也通过还原亚硝酸盐或硝酸盐形成NO。但 NO形成的NOS非依赖性途径在缺血后损伤调节中的性质和作用， 不清楚因此，本项目将表征这些NO形成过程及其氧化剂 交互.研究将首先在酶水平上进行，然后在内皮细胞中进行，然后在细胞水平上进行。 在离体心脏模型中的研究以及最终在冠状动脉闭塞和再流的体内模型中的研究。这个项目 有以下五个具体目标。1)为了表征O2~和O2~ -衍生氧化剂的作用机理， 影响人内皮型一氧化氮合酶（eNOS）的结构和功能。2)通过以下方式确定机制： 其中-O2-和-O2 -衍生的氧化剂改变离体缺血后心脏中eNOS的结构和功能 并评估恢复eNOS功能的方法。3)为了表征亚硝酸盐的基本机制， 硝酸盐或有机硝酸盐介导的NO生成。4)表征亚硝酸盐或硝酸盐介导的作用 在离体缺血后心脏中NO产生的途径及其调节机制 过程5)用于抑制氧化损伤、恢复和/或治疗的新型治疗剂的体内测试和EPR/NMR共成像 NOS的功能和赋予心肌保护。对于这些目标; EPR，电化学，和 将进行氧自由基、NO和NO衍生物质的化学发光测量 沿着对NO发生临界点的功能、结构和修饰的表征 内切酶总的来说，这个项目将确定氧自由基和代谢途径之间的相互作用。 NO的产生发生在缺血后损伤的过程中，并导致最佳的发展 挽救处于危险中的心肌的策略。

Oxygen radical generation is increased in the postischemic heart and leads to altered nitric oxide (NO) production and postischemic injury. Using Electron Paramagnetic Resonance (EPR) and other techniques, we directly measured the mechanisms of oxygen radical and NO generation in the postischemic heart. From these and other recent studies, it has been shown that oxidants alter NO generation from nitric oxide synthase (NOS). However, the precise role of oxidants in the regulation of NOS structure and function remains unknown. Recently, it has been shown that under ischemic conditions oxygen radical generating enzymes, such as xanthine oxidase (XO), also form NO through reduction of nitrite or nitrate. However, the nature and role of NOS-independent pathways of NO formation in the modulation of postischemic injury is unclear. Therefore, this project will characterize these processes of NO formation and their oxidant interactions. Studies will be performed first at the enzyme level; then in endothelial cells, followed by studies in isolated heart models and finally in vivo models of coronary occlusion and reflow. This project has the following 5 specific aims. 1) To characterize mechanisms by which 'O2~ and 'O2~ -derived oxidants affect the structure and function of human endothelial NOS (eNOS). 2) To determine the mechanism by which -O2" and 'O2 -derived oxidants alter eNOS structure and function in the isolated postischemic heart and evaluate approaches to restore eNOS function. 3) To characterize fundamental mechanisms of nitrite, nitrate or organic nitrate mediated NO generation. 4) To characterize the role of nitrite or nitrate mediated pathways of NO generation in the isolated postischemic heart and the mechanisms that regulate this process. 5) In vivo testing and EPR/NMR coimaging of novel therapeutics to inhibit oxidant injury, restore NOS function and confer myocardial protection. For these aims; EPR, electrochemical, and chemiluminescence measurements of oxygen radicals, NO, and NO derived species will be performed along with characterization of the function, structure and modification of the critical NO generating enzymes. Overall, this project will determine the interactions between oxygen radicals and the pathways of NO generation that occur in the process of postischemic injury, and lead to the development of optimal strategies to salvage heart muscle at risk.