NO-Mediated Pulmonary Vasodilation After Chronic Hypoxia

慢性缺氧后NO介导的肺血管舒张

• 批准号: 6908966
• 负责人: THOMAS C RESTA
• 金额: $ 33.75万
• 依托单位: UNIVERSITY OF NEW MEXICO
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6908966
• 关键词: biological signal transduction; cGMP dependent protein kinase; calcium channel; calcium flux; calcium ion; enzyme activity; ionomycin; laboratory rat; lung ischemia /hypoxia; nitric oxide; pulmonary circulation; pulmonary hypertension; serine threonine protein kinase; thapsigargin; vascular smooth muscle; vasodilation

DESCRIPTION (provided by applicant): Chronic hypoxia (CH) associated with various lung diseases leads to pulmonary hypertension. Adaptive responses, including enhanced nitric oxide (NO)-mediated vasodilation, may diminish the severity of hypoxic pulmonary hypertension. However, neither the mechanism of altered NO-dependent reactivity following CH, nor the signaling pathways leading to NO-mediated pulmonary vasodilation are well understood. Protein kinase G (PKG) is a prominent target of NO signaling that elicits relaxation of vascular smooth muscle (VSM) by decreasing the concentration of intracellular free calcium ([Ca 2+]i)as well as desensitization of the contractile apparatus to Ca 2+ . This latter effect of PKG to cause Ca2+-desensitization is largely undefined, although studies have implicated a role for inactivation of the RhoA-Rho kinase-signaling cascade in this response. Interestingly, pilot experiments suggest that CH attenuates PKG-dependent decreases in VSM [Ca 2+]i while paradoxically augmenting PKG-mediated vasodilation. Therefore, the proposed studies will investigate the central hypothesis that CH impairs PKG-dependent regulation of [Ca2+]i in pulmonary VSM and mediates a compensatory shift in PKG signaling to promote desensitization of the contractile apparatus to [Ca 2+]. This hypothesis will be addressed by the following specific aims: Specific Aim #1: Establish the mechanism by which CH impairs PKG-dependent reduction of pulmonary VSM [Ca2+]i. The working hypothesis for this aim is that CH diminishes PKG-mediated decreases in VSM [Ca2+]i by interfering with regulation of Ca 2+ influx and sequestration mechanisms. Specific Aim #2: Identify the mechanism by which CH augments PKG-mediated pulmonary VSM Ca2+-desensitization. We hypothesize that enhanced PKG-mediated pulmonary vasodilation following CH is a function of VSM Ca2+-desensitization through inhibition of the RhoA-Rho kinase pathway. The proposed studies will employ an innovative approach to address mechanisms by which CH alters PKG-signaling in pulmonary VSM, including simultaneous measurement of vasoreactivity and VSM [Ca2+]i in isolated, pressurized small pulmonary arteries from control and CH rats. Findings from studies are expected to fundamentally advance our understanding of signal transduction mechanisms by which PKG regulates pulmonary vascular tone, as well as adaptive responses of the pulmonary circulation to CH.

描述（由申请人提供）：与各种肺部疾病相关的慢性缺氧（CH）会导致肺动脉高压。适应性反应，包括增强一氧化氮（NO）介导的血管舒张，可能会减轻缺氧性肺动脉高压的严重程度。然而，CH 后 NO 依赖性反应性改变的机制，以及导致 NO 介导的肺血管舒张的信号通路均不清楚。蛋白激酶 G (PKG) 是 NO 信号传导的重要靶标，可通过降低细胞内游离钙 ([Ca 2+]i) 的浓度以及收缩装置对 Ca 2 的脱敏来引起血管平滑肌 (VSM) 松弛+ . PKG 导致 Ca2+ 脱敏的后一种作用在很大程度上尚不清楚，尽管研究表明 RhoA-Rho 激酶信号级联失活在该反应中发挥作用。有趣的是，初步实验表明，CH 减弱了 VSM [Ca 2+]i 中 PKG 依赖性的降低，同时反而增强了 PKG 介导的血管舒张。因此，拟议的研究将调查以下中心假设：CH 损害肺 VSM 中 [Ca2+]i 的 PKG 依赖性调节，并介导 PKG 信号传导的代偿性转变，以促进收缩装置对 [Ca 2+] 的脱敏。该假设将通过以下具体目标来解决： 具体目标#1：建立 CH 损害 PKG 依赖性肺 VSM [Ca2+]i 减少的机制。该目标的工作假设是，CH 通过干扰 Ca 2+ 流入和隔离机制的调节来减少 PKG 介导的 VSM [Ca2+]i 减少。具体目标#2：确定 CH 增强 PKG 介导的肺 VSM Ca2+ 脱敏的机制。我们假设 CH 后 PKG 介导的肺血管舒张增强是 VSM Ca2+ 通过抑制 RhoA-Rho 激酶途径实现脱敏的功能。拟议的研究将采用创新方法来解决 CH 改变肺 VSM 中 PKG 信号传导的机制，包括同时测量对照组和 CH 大鼠的孤立加压小肺动脉中的血管反应性和 VSM [Ca2+]i。研究结果有望从根本上增进我们对 PKG 调节肺血管张力的信号转导机制以及肺循环对 CH 的适应性反应的理解。