Regulation of pulmonary circulation in fetus and newborn

项目摘要 新生儿持续性肺动脉高压(PPHN)是一种由以下原因引起的疾病 肺血管扩张在出生时发生。受影响的婴儿患有低氧血症，风险增加。 死亡和长期残疾的风险。产前诱导胎羊PPHN模型的研究 胆管狭窄表现为NO释放减少和氧化应激增加 肺动脉。NADPH氧化酶的激活与内皮一氧化氮的解偶联活性 合酶(ENOS)是PPHN中肺动脉超氧化物歧化(O2？)的来源。线粒体 氧气消耗是血管细胞产生氧气的重要来源。氧气含量增加 出生时的可获得性和氧化磷酸化可能导致活性氧物种增加 (ROS)。然而，线粒体ROS对PPHN氧化应激的贡献是 未知。暴露于一氧化氮合酶激动剂三磷酸腺苷和出生后氧分压刺激这种联系 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)。这个部位的靶向NO释放调节氧化的速率 磷酸化以减少正常胎儿PAEC的O2-产生。锰的表达 超氧化物歧化酶(MnSOD)在PPHN中也降低。我们建议调查这部小说 内皮型一氧化氮合酶降低线粒体外膜靶向性的假说 MnSOD的表达导致线粒体O2-的过量生成和猝灭。 线粒体O2-反过来又会损害出生时的肺血管扩张。的广泛而具体的目标 建议的研究是：(1)研究eNOS-线粒体相互作用的变化和 MnSOD在PPHN中的表达及其对产后耗氧量、NO和O2-水平的影响 PAEC的转化；(2)探讨PPHN内皮型一氧化氮合酶靶向线粒体的机制 (3)探讨线粒体氧化应激在肺血管扩张受损中的作用 以及PPHN出生相关转变过程中的氧合作用。将在PAEC和肺脏中进行研究 产前结扎动脉导管(PPHN)和假结扎的羔羊动脉 控制。研究还将在有或没有PPHN的完整胎羊身上进行，这些羊在足月至 探讨线粒体O2-在大鼠肺循环和氧合变化中的作用 出生。这些研究将确定PPHN中一个重要的新的氧化应激源。这些 观察可能导致新的靶向治疗，以改善PPHN的血管扩张和氧合。

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.