Regulation of pulmonary circulation in fetus and newborn

项目摘要 新生儿持续性肺动脉高压（PPHN）是一种由于呼吸衰竭而导致的疾病。 肺血管扩张发生在出生时。受影响的婴儿是低氧血症和风险增加 死亡率和长期残疾。产前药物诱导胎羊PPHN模型的研究 导管收缩表明NO释放减少，氧化应激增加， 肺动脉NADPH氧化酶激活与内皮细胞一氧化氮解偶联活性 eNOS合成酶（eNOS）是PPHN肺动脉中超氧化物（O2 <$-）的来源。线粒体 氧消耗是血管细胞中O2-产生的重要来源。增加O2 出生时的可用性和氧化磷酸化可能导致活性氧增加 (ROS)在线粒体中。然而，线粒体ROS对PPHN氧化应激的贡献是 未知暴露于ATP（一种NOS激动剂）和出生后氧张力刺激了这种关联 正常胎羊肺动脉内皮型一氧化氮合酶与线粒体外膜蛋白、孔蛋白的关系 内皮细胞（PAEC）。在这个位置有针对性的NO释放调节氧化的速率， 磷酸化减少正常胎儿PAEC中O2？-的产生。锰的表达 超氧化物歧化酶（MnSOD）在PPHN中也降低。我们打算调查这部小说 假设eNOS对线粒体外膜的靶向性降低， MnSOD的表达导致线粒体O2 <$-的过度生成和猝灭减少。 线粒体中的O2-反过来又会损害出生时的肺血管舒张。广泛的具体目标 拟开展的研究包括：（1）研究eNOS-线粒体相互作用的改变， MnSOD在PPHN中的表达及其对O2消耗、NO和O2-水平的影响 （2）探讨PPHN中eNOS靶向线粒体改变的机制 探讨线粒体氧化应激在肺血管舒张功能受损中的作用 和氧合在PPHN中与出生相关的过渡期间。将在PAEC和肺动脉中进行研究 从产前结扎动脉导管（PPHN）和假结扎的羔羊中采集动脉 对照还将在足月分娩的完整胎羊（有或无PPHN）中进行研究， 研究线粒体O2 <$-在肺循环和氧合转换中的作用， 出生这些研究将确定PPHN中氧化应激的重要新来源。这些 观察可能导致新的靶向治疗，以改善PPHN的血管舒张和氧合。

Project Summary Persistent pulmonary hypertension of the newborn (PPHN) is a condition that results from failure of pulmonary vasodilation to occur at birth. The affected infants are hypoxemic and have increased risks of mortality and long-term disabilities. Studies in a fetal lamb model of PPHN, induced by prenatal ductal constriction demonstrated a decrease in NO release and increase in oxidative stress in pulmonary arteries. Activation of NADPH oxidase and uncoupled activity of endothelial nitric oxide synthase (eNOS) are sources of superoxide (O2¿-) in the pulmonary arteries in PPHN. Mitochondrial oxygen consumption is an important source of O2¿- generation in vascular cells. Increase in O2 availability and oxidative phosphorylation at birth may lead to increased reactive oxygen species (ROS) in mitochondria. However, the contribution of mitochondrial ROS to oxidative stress in PPHN is unknown. Exposure to ATP, a NOS agonist, and postnatal oxygen tension stimulate the association of eNOS with the mitochondrial outer membrane protein, porin in normal fetal lamb pulmonary artery endothelial cells (PAEC). Targeted NO release in this location regulates the rate of oxidative phosphorylation to decrease O2¿- production in normal fetal PAEC. The expression of manganese superoxide dismutase (MnSOD) is also decreased in PPHN. We propose to investigate the novel hypothesis that decreased targeting of eNOS to mitochondrial outer membrane and decreased expression of MnSOD lead to excess generation and decreased quenching of mitochondrial O2¿-. The mitochondrial O2¿- in turn impairs pulmonary vasodilation at birth. The broad specific aims of the proposed studies are to (1) Investigate the alterations in eNOS-mitochondrial interactions and MnSOD expression in PPHN and its effect on O2 consumption, NO and O2¿- levels during postnatal transition of PAEC, (2) Investigate the mechanism of altered eNOS targeting to mitochondria in PPHN and (3) investigate the role of mitochondrial oxidative stress in the impaired pulmonary vasodilation and oxygenation during birth-related transition in PPHN. Studies will be done in PAEC and pulmonary arteries harvested from lambs with prenatal ligation of ductus arteriosus (PPHN) and in sham ligation controls. Studies will be also done in intact fetal lambs with or without PPHN delivered at term to investigate the role of mitochondrial O2¿- in the transition of pulmonary circulation and oxygenation at birth. These studies will identify an important new source of oxidative stress in PPHN. These observation may lead to new targeted therapies to improve vasodilation and oxygenation in PPHN.