NO-Mediated Pulmonary Vasodilation After Chronic Hypoxia

慢性缺氧后NO介导的肺血管舒张

• 批准号: 7081293
• 负责人: THOMAS C RESTA
• 金额: $ 32.96万
• 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/7081293
• 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）：慢性缺氧（CH）与各种肺部疾病相关，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，可能减轻低氧性肺动脉高压的严重程度。然而，CH后一氧化氮依赖性反应性改变的机制以及导致一氧化氮介导的肺血管舒张的信号通路都没有得到很好的理解。蛋白激酶G （PKG）是NO信号的一个重要靶点，通过降低细胞内游离钙（[ca2 +]i）的浓度以及收缩器官对ca2 +的脱敏，引发血管平滑肌（VSM）的松弛。PKG引起Ca2+脱敏的后一种作用在很大程度上是不明确的，尽管研究暗示了在这种反应中RhoA-Rho激酶信号级联的失活作用。有趣的是，初步实验表明，CH减弱了pkg依赖性的VSM [ca2 +]i的下降，同时矛盾地增强了pkg介导的血管舒张。因此，提出的研究将探讨CH损害肺VSM中PKG依赖性的[Ca2+]i调节，并介导PKG信号的代偿性转移，以促进收缩装置对[Ca2+]的脱敏的中心假设。这一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+]减少的机制。这一目标的工作假设是，CH通过干扰Ca2+内流和固存机制的调节，减少了pkg介导的VSM [Ca2+]i的减少。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通过抑制RhoA-Rho激酶途径实现VSM Ca2+脱敏的功能。拟议的研究将采用一种创新的方法来解决CH改变肺VSM中pkg信号传导的机制，包括在对照和CH大鼠分离的加压小肺动脉中同时测量血管反应性和VSM [Ca2+]i。研究结果有望从根本上推进我们对PKG调节肺血管张力的信号转导机制的理解，以及肺循环对CH的适应性反应。