Mechanism of cGMP-Mediated Vasodilation in Perinatal Lung

描述(申请人提供)：我们和其他人已经证实，内皮细胞衍生的一氧化氮-鸟苷酸环化酶-cGMP途径是从胎儿状态向新生儿状态转变过程中肺循环血管扩张的重要机制。本实验室首次证实cGMP依赖的蛋白激酶(PKG)在介导cGMP在肺循环中的作用中起着至关重要的作用。我们还表明，cAMP可以交叉激活PKG，因此PKG似乎介导了这两种环核苷酸的血管扩张作用。出生时肺血管扩张的一个重要信号是氧分压的突然增加。我们有数据表明，当胎儿肺血管暴露在氧气增加时，PKG活性增加，导致对cGMP的扩张器反应增强。我们的初步数据表明，绵羊胎肺血管平滑肌细胞(PVSMC)暴露在高氧环境中，结果如下：1.PKG激酶活性增加，2.PKG蛋白水平增加，3.PKG mRNA水平增加。我们的假设是，在出生时，氧气上调PKG蛋白水平和PKG激酶活性，从而促进肺血管扩张和新生儿平稳过渡。我们的目的是：1.研究氧对PVSMC中PKG激酶活性的调节作用；2.确定氧对PVSMC中PKG蛋白水平的影响；3.探讨氧对PVSMC中PKG蛋白和mRNA水平的两种调节机制。实验将从绵羊胎儿的动脉和静脉中分离出PVSMC。我们还将利用分离的绵羊胎儿肺内动静脉，用PVSMC模拟实验，从而确定体外生化数据的生理意义。我们的总体目标是更好地了解围产期肺血管舒缩张力调节的独特生物学过程，并了解PKG在这一过程中的作用。从我们的研究中获得的知识应该使我们能够开发新的预防和治疗策略来预防和治疗出生时的肺血管运动控制障碍，如新生儿持续性肺动脉高压。

DESCRIPTION (provided by applicant): We and others have established that the endothelium derived nitric oxide-guanylyl cyclase-cGMP pathway is an important mechanism of vasodilation in the pulmonary circulation during the transition from fetal to newborn state. Our laboratory was first to establish that cGMP-dependent protein kinase (PKG) is critically important for mediating the action of cGMP in the pulmonary circulation. We have also shown that cAMP can cross-activate PKG and thus it appears that PKG mediates the vasodilator action of both cyclic nucleotides. An important signal for the pulmonary vasculature to dilate at birth is the abrupt increase in oxygen tension. We have data to show that when fetal pulmonary vessels are exposed to increased oxygen, there is an increase in PKG activity leading to an enhanced dilator response to cGMP. Our preliminary data show that exposure of ovine fetal pulmonary vascular smooth muscle cells (PVSMC) to increased oxygen results in: 1. An increase in PKG kinase activity, 2. An increase in PKG protein levels, as well as 3. An increase in PKG mRNA levels. Our hypothesis is that at birth, oxygen up-regulates PKG protein levels and PKG kinase activity, thereby facilitating pulmonary vasodilation and a smooth neonatal transition. Our aims are: 1. To investigate how oxygen regulates PKG kinase activity in PVSMC; 2. To determine the effect of oxygen on PKG protein levels in PVSMC; and 3. To investigate two mechanisms of regulation of PKG protein and mRNA levels in PVSMC. Experiments will be done in ovine fetal PVSMC from arteries and veins. We will also use isolated ovine fetal intrapulmonary arteries and veins, to model the experiments with PVSMC, so that we can determine the physiological significance of the in vitro biochemical data. Our overall goal is to gain a better understanding of the unique biological processes by which pulmonary vasomotor tone is regulated in the perinatal period and to understand the role of PKG in this process. Knowledge derived from our studies should enable us to develop new prevention and treatment strategies for disorders of pulmonary vasomotor control at birth such as Persistent Pulmonary Hypertension of the Newborn.