Pulmonary Endothelial Function During Chronic Hypoxia

慢性缺氧期间的肺内皮功能

• 批准号: 6979873
• 负责人: BENJIMEN R WALKER
• 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: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6979873
• 关键词: calcium flux; endothelin; enzyme activity; enzyme induction /repression; hypoxia; laboratory rat; lung ischemia /hypoxia; mechanical stress; membrane potentials; nitric oxide; nitric oxide synthase; pulmonary artery; pulmonary hypertension; respiratory circulation; shear stress; vascular endothelium; vascular resistance; vasoactive agent; vasoconstriction

DESCRIPTION (provided by applicant): The long-term goal of our research is to determine the nature of the derangements in endothelial function that occur with CH-induced pulmonary hypertension. Our previous work has established that eNOS expression is selectively elevated in the arterial segments of the pulmonary circulation that demonstrate vascular remodeling and elevated vascular resistance. Our data suggest that this upregulation of eNOS expression is the result of altered mechanical forces associated with remodeling, such as elevated shear stress or intraluminal pressure. It is likely that these stimuli or hypoxia per se could influence endothelial cell Em and calcium influx as well. Indeed, in pilot experiments presented below we document endothelial depolarization and lower [Ca2+]j in intact small pulmonary arteries from CH-exposed rats compared to controls. In addition, we have found that VSMC Em is relatively depolarized in pulmonary arteries from CH rats compared to controls, even when vessels are acutely returned to normoxia. There is evidence in other beds that electrical coupling between VSMCs and endothelial cells exists, such that the endothelial cell Em could be influenced by effects of CH on VSMC Em. In addition, we have evidence that calcium entry pathways may be diminished following CH, which could also contribute to lowered [Ca2+]j. The objective of the present proposal is to determine the effects of CH on pulmonary endothelial calcium homeostasis, testing the central hypothesis that CH exposure leads to endothelial cell depolarization and decreased calcium influx. The planned experiments will establish the factors that constrain activity of calcium-sensitive endothelial pathways such as NO production in this clinically relevant setting. Our laboratory has developed an array of techniques necessary to clearly assess this question, including the measurement of endothelial cell calcium and Em in intact small intrapulmonary arteries from control and CH-exposed animals as well as single cell electrophysiology and calcium imaging methodology.

描述（由申请人提供）：我们研究的长期目标是确定CH诱导的肺动脉高压造成的内皮功能中的扰动的性质。我们以前的工作已经确定，eNOS表达在肺循环的动脉片段中有选择地升高，该肺循环表现出血管重塑和升高的血管耐药性。我们的数据表明，eNOS表达的上调是与重塑相关的机械力改变的结果，例如剪切应力升高或腔内压力。这些刺激或缺氧本身可能也可能影响内皮细胞EM和钙流入。实际上，与对照组相比，在下面提出的试验实验中，我们记录了来自CH暴露大鼠的完整小肺动脉的内皮去极化和较低的[Ca2+] J。此外，我们发现与对照组相比，VSMC EM在CH大鼠的肺动脉中相对去极化，即使血管急性恢复到常氧。在其他床中有证据表明，VSMC和内皮细胞之间存在电耦合，因此内皮细胞EM可能会受到CH对VSMC EM的影响的影响。此外，我们有证据表明，CH后钙进入途径可能会减少，这也可能有助于降低[Ca2+]J。本提案的目的是确定CH对肺部内皮钙稳态的影响，检验了CH暴露导致内皮细胞去极化和钙涌入钙的中心假设。计划的实验将建立限制对钙敏感的内皮途径活性的因素，例如在这种临床相关的环境中没有产生的因素。我们的实验室已经开发了一系列需要清楚评估这个问题的技术，包括在对照和CH暴露动物的完整小肺内动脉中测量内皮细胞钙和EM，以及单个细胞电生理学和钙成像方法。