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海拔长期缺氧（LTH）改变胎儿和成人脑血管的基本机制。我们还将研究这些与胎儿到成人发育有关的机制。这个项目基础广泛，多学科，垂直整合了生理学、细胞学、生物化学和分子方法。基于二十年的研究，我们将在适应高海拔的绵羊身上测试一些假设。总的假设是，高海拔，长期缺氧与脑血管收缩反应的改变有关，继发于α -肾上腺素能受体（或AR）亚型和/或特异性蛋白激酶C亚型（PKC）介导的下游Ca2+依赖性和Ca非依赖性信号转导途径的改变。一个相关的假设是，与成人的“收缩”表型相比，LTH显著改变了oi - ar亚型和特异性PKC同功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。四个特定目的将探讨LTH在脑动脉Or中的作用

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.