OXIDANTS, ENERGY AND PULMONARY VASCULAR DEVELOPMENT

(改编自申请摘要)能量代谢受损 高氧暴露可能对肺部产生重要的负面后果 生长发育与功能不佳等新生儿 支气管肺发育不良的发达、伤痕累累的肺。这种可能性 常压高氧严重抑制了能量代谢 一直是一个颇具争议的问题。然而，最近的 三元酸循环关键酶乌头酸酶的鉴定 作为一个被高氧迅速而有效地抑制的靶点，提供了 这种损害的一个例子可能会对 肺的生长和功能。它假设失活的 关键的三元酸循环酶乌头酸酶是高氧的关键 抑制能量(ATP)产生的事件，从而抑制肺 早产儿的细胞生长和功能。一氧化氮也可能 在这一进程中发挥贡献作用。此外，还提议 这个过程在早产儿中可能被夸大了，因为缺乏 重要的肺部抗氧化剂防御。此外，还建议 抑制乌头酸酶失活或增强其活性的干预 它的重新激活或通过其促进能量生产 替代机制，将恢复肺细胞的生长和功能。为了测试 这些假说，孕晚期胎鼠肺泡上皮细胞 在基质上生长，在一些研究中，在存在的情况下共培养 漂浮过滤器上的活基质细胞，或胎儿肺外植体，将 被利用了。 高氧和强效氧对乌头酸酶的抑制作用 特异性抑制剂氟柠檬酸对能量产生、生长、细胞工作的影响 如表面活性物质蛋白表达和脂肪产生，以及表达 上皮源性生长因子在肺血管中的关键作用 如血管内皮生长因子(VEGF)等的开发都将 评估过了。核磁共振及其他分析生化 将使用技术来实时确定能源和 持续暴露在高氧或其他环境中的中间代谢产物 氟氯硝酸盐。在牛胎肺血管内皮细胞中， 乌头酸酶抑制对细胞能量状态、生长和生长的影响 相关功能(血管内皮生长因子受体的表达)将被评估。此外， 血管壁、平滑肌等其他细胞类型的敏感性 和成纤维细胞，由于能量损伤和生长抑制 将乌头酸酶的抑制率进行比较。基于这些研究，抗氧化剂 可降低因高氧而使乌头酸酶失活的干预措施，或 增加它的重新激活，将被评估为潜在的姑息性 效果。通过新的方法，这些研究将提供新的 关于高氧损害能量的机制的信息 肺内的代谢，改变肺血管的生长和 发展。 此外，姑息疗法也可能因此被开发出来。

(Adapted from the application's abstract) Impaired energy metabolism due to hyperoxic exposure may have important negative consequences for lung growth, development and function in the newborn such as the poorly developed, scarred lungs of bronchopulmonary dysplasia. The possibility that energy metabolism is seriously inhibited by normobaric hyperoxia has been an issue of considerable controversy. However, the recent identification of the critical tricarboxylic acid cycle enzyme aconitase as a target which is rapidly and potently inhibited by hyperoxia provides one example of such an impairment which may have devastating effects on lung growth and function. It is hypothesized that inactivation of the critical tricarboxylic acid cycle enzyme aconitase by hyperoxia is a key event which inhibits energy (ATP) production, and , consequently, lung cell growth and function in the premature newborn. Nitric oxide also could play a contributory role in this process. Further, it is proposed that this process may be exaggerated in the premature due to a deficiency of important lung antioxidant defenses. In addition, it is suggested that interventions which either inhibit aconitase inactivation or potentiate its re-activation or which facilitate energy production through its alternative mechanism, will restore lung cell growth and function. To test these hypothesis, alveolar epithelial cells from late gestation fetal rat grown on matrix, and, in some studies, co-cultured in the presence of living matrix cells on floating filters, or fetal lung explants, will be utilized. The effects of inhibition of aconitase both by hyperoxia and by the potent specific inhibitor fluorocitrate on energy production, growth, cell work such as surfactant protein expression and lipid production, and expression of epithelium-derived growth factors critical in pulmonary vascular development such as vascular endothelial growth factor (VEGF) all will be assessed. Nuclear magnetic resonance and other analytical biochemical techniques will be used to make real-time determinations of energy and intermediary metabolites during ongoing exposure to hyperoxia or flurocitrate. In bovine fetal pulmonary vascular endothelial cells, the effect of aconitase inhibition on cell energy status, growth, and growth- related function (expression of VEGF receptors) will be assessed. Further, the sensitivity of other cell types of the vascular wall, smooth muscle and fibroblast, to energy impairment and growth inhibition due to aconitase inhibition will be compared. Based on these studies, antioxidant interventions which may decrease aconitase inactivation by hyperoxia, or increase it re-activation, will be evaluated for potential palliative effects. Through novel approaches, these studies will provide new information about the mechanisms by which hyperoxia impairs energy metabolism in the lung and alters pulmonary vascular growth and development. In addition, palliative therapies could be developed as a result.