CEREBROVASCULAR CONTRACTILE RESPONSES TO HIGH ALTITUDE LONG TERM HYPOXIA

该项目的总体主题是了解如何适应高原长期缺氧(LTH)改变胎儿和成人脑血管系统的基本机制。我们还将研究这些机制与从胎儿到成人的发育相关。这个项目是广泛的、多学科的，并使用生理学、细胞、生化和分子方法进行垂直整合。在二十年的研究基础上，我们将在适应高海拔的绵羊身上检验一些假设。总的假设是，高原长期低氧与脑血管收缩反应的改变有关，继而发生改变的是α-肾上腺素能受体(AR)亚型和/或特定的蛋白激酶C亚型(PKC)介导的下游钙依赖和钙非依赖性信号转导通路。与成人“收缩”表型相比，LTH显著改变了OI-AR亚型和特异性PKC同工酶介导的原癌基因和代表血管平滑肌“合成”和/或“增殖”表型的基因的表达。四个特定的目标将研究LTH在大脑动脉或大脑中的作用 肾上腺素能介导的细丝和粗丝的信号转导，如1)OI-AR、PKC亚型、细胞外信号调节蛋白(ERKs)和下游效应蛋白的作用，2)质膜和肌浆网钙通道的作用，3)血管表型的基因调控，以及4)信号通路基因/蛋白的发现。在这些研究中，我们将使用激动剂诱导的收缩和细胞内[Ca+]、免疫印迹、RT-PCR、RNAi沉默、共聚焦显微镜、2D-Gel-MS和基因微阵列/通路分析。从科学上讲，这些研究将增强我们对胎儿和成人脑血管适应LTH的基本机制的理解。他们还将说明从胎儿到成人发育的各个方面。临床上，这些研究至少涉及三个关键问题。1)对于胎儿和新生儿，它们与对长期缺氧的反应有关，如生活在高海拔地区的妇女，以及患有心脏病或肺病的吸烟或贫血的妇女；对于新生儿，它们与脑血管血流改变并伴有脑出血和肺动脉高压有关。2)他们还将有助于理解心血管疾病的机制和成人疾病的更新换代“规划”。3)对急性高原反应、先兆子痫、高原脑和肺水肿等疾病的发病机制有一定的认识。

The overall theme of this project is to understand whereby acclimatization to high altitude long-term hypoxia (LTH) alters fundamental mechanisms in the cerebrovasculature of the fetus and adult. We also will examine these mechanisms in association with development from fetus to adult. This project is broadly based, multidisciplinary, and vertically integrated using physiologic, cellular, biochemical, and molecular approaches. Based on two decades of research, we shall test a number of hypotheses in sheep acclimatized to high altitude. The overall hypothesis is that high altitude, long-term hypoxia is associated with changes in cerebrovascular contractile responses secondary to altered alphai-adrenergic-receptor (or AR) subtypes and/or specific protein kinase C isoforms (PKC)-mediated downstream Ca2+-dependent and Ca -independent signal transduction pathways. An associated hypothesis is that LTH significantly alters Oi-AR-subtype- and specific PKC isozyme-mediated expression of proto-oncogenes and genes representing vascular smooth muscle "synthetic" and/or "proliferative" phenotypes, as compared to those of adult "contractile" phenotype. Four specific aims will examine the role of LTH in cerebral artery Or adrenergic-mediated signal tranduction of thin and thick myofilament, e.g., 1) roles of Oi-AR, PKC isoforms, extracellular signal regulated kinases (ERKs), and downstream effector proteins, 2) the role of plasma membrane and sarcoplasmic reticulum Ca2+ channels, 3) gene regulation of vascular phenotypes, and 4) signaling pathways gene/protein discovery. For the studies we will utilize agonist-induced contractility and intracellular [Ca2+], Western immunobiots, RT-PCR, RNAi silencing, confocal microscopy, 2D-gel-mass spectroscopy, and gene microarray/pathways analysis. Scientifically the studies will augment our understanding of basic mechanisms whereby fetal and adult cerebral vessels acclimatize to LTH. They also will illustrate aspects of development from fetus to adult. Clinically the studies relate to at least three critical problems. 1) For the fetus and newborn they relate to responses to prolonged hypoxia as occurs in women who live at high altitude, as well as those who smoke or are anemic, who have heart or lung disease; for the newborn altered cerebrovascular blood flow with intracerebral hemorrhage and pulmonary hypertension. 2) They also will contribute to understanding mechanisms of cardiovascular disorders and renatal "programming" of adult disease. 3) Finally, they are relevant to understanding mechanisms of diseases such as: Acute Mountain Sickness, Preeclampsia, and High Altitude Cerebral and Pulmonary Edema.