EARLY EFFECTS OF OXYGEN ON LUNG METABOLIC FUNCTION

氧气对肺代谢功能的早期影响

• 批准号: 3347828
• 负责人: DAVID J BASSETT
• 金额: $ 9.6万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-07-01 至 1988-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3347828
• 关键词: NAD(P)H dehydrogenase; adenosine triphosphate; antioxidants; bioenergetics; cell type; cellular pathology; cytotoxicity; early diagnosis; electron microscopy; fatty acid biosynthesis; glucose 6 phosphate; glutathione; glyceraldehyde 3 phosphate dehydrogenase; glycolysis; histopathology; hyperoxia; lung disorder; microscopy; mitochondria; molecular site; morphology; nutrition related tag; oxidation reduction reaction; oxidative phosphorylation; oxygen tension; pathologic process; pentose phosphate; pulmonary edema; pyruvate dehydrogenase; radiotracer; respiratory epithelium; respiratory function; scintillation counter; spectrometry; thin layer chromatography; toxicant interaction; vitamin E deficiency

It is well established that exposure of experimental animals to a hundred percent oxygen for longer than 24 hours results in adverse alterations of lung structure and function. It has been proposed that the observed cytotoxicity of alveolar epithelium and capillary endothelium result from oxygen free radical interactions with cell membranes and key enzyme proteins involved in the maintenance of ATP and the antioxidant reduced glutathione. Although in vitro studies with homogenates and subcellular fractions have suggested that the sulphydryl containing dehydrogenases of glyceraldehyde-3-phosphate, pyruvate, and glucose-6-phosphate are particularly sensitive to oxygen inactivation, few studies have examined whether such inactivations occur in the intact organ. It is the purpose of this study to use an isolated perfused rat lung preparation to assess those changes in metabolic function that occur prior to observable alterations in pathology and physiological function, resulting from 100% oxygen exposures. The specific hypothesis states that oxygen inactivates key metabolic enzymes involved in lung intermediary metabolism, and such inhibitions are initially reversible on cessation of exposure. Intracellular sites of oxygen interaction will be identified by in vitro measurements of glycolytic, pentose cycle and mitochondrial pathway fluxes in isolated perfused lungs isolated from normal and vitamin E deficient rats during the first 48 hours of in vivo exposure to 100% oxygen. Since perfusions with uncouplers and electron acceptors enhance tissue ATP and NADPH utilizations respectively, they will be used to define maximal metabolic fluxes. Such an approach, by providing an estimate of reserve capacity, represents a more sensitive method to examine early metabolic impairments, than has previously been possible with other in vitro systems. To establish whether glutathione is involved in preventing oxygen inactivation of lung sulphydryl 1 enzymes, lungs will also be perfused under conditions of limited glutathione supply, brought about by perfusion with t-butylhydroperoxide. Metabolic changes will be evaluated in lungs at different times after cessation of exposure in order to establish reversibility. These studies, therefore, provide a better understanding of the mechanisms of oxygen interaction, needed for future early detection and prevention of oxidant lung injuries.

众所周知，实验动物暴露于一百种 氧气百分比超过 24 小时会导致 肺的结构和功能。 有人建议观察到 肺泡上皮和毛细血管内皮的细胞毒性是由 氧自由基与细胞膜和关键酶的相互作用 参与维持 ATP 和抗氧化剂减少的蛋白质 谷胱甘肽。 尽管用匀浆和亚细胞进行体外研究 分数表明含有巯基的脱氢酶 3-磷酸​​甘油醛、丙酮酸和 6-磷酸葡萄糖是 对氧失活特别敏感，很少有研究考察过 这种失活是否发生在完整的器官中。 其目的是 本研究使用分离的灌注大鼠肺制剂来评估这些 在可观察到的改变之前发生的代谢功能的变化 100% 氧气带来的病理和生理功能 曝光。 具体的假设指出，氧气使关键的失活 参与肺中间代谢的代谢酶等 停止接触后，抑制最初是可逆的。 氧相互作用的细胞内位点将通过体外鉴定 糖酵解、戊糖循环和线粒体途径通量的测量 在与正常和维生素 E 缺乏者分离的隔离灌注肺中 大鼠体内暴露于 100% 氧气的前 48 小时。 自从 解偶联剂和电子受体的灌注增强组织 ATP 和 NADPH 利用率分别，它们将用于定义最大 代谢通量。 这种方法通过提供储量估计 能力，代表了一种更灵敏的方法来检查早期代谢 损伤，比以前可能的其他体外 系统。 确定谷胱甘肽是否参与阻止缺氧 肺巯基1酶失活，肺也会被灌注 在灌注引起的谷胱甘肽供应有限的情况下 与叔丁基氢过氧化物。 将在肺部评估代谢变化 停止暴露后的不同时间，以确定 可逆性。 因此，这些研究可以更好地理解 未来早期检测所需的氧相互作用机制 预防氧化性肺损伤。