CARDIOPULMONARY SURGERY RESEARCH

心肺外科研究

• 批准号: 7103498
• 负责人: Philip J Kadowitz
• 金额: $ 29万
• 依托单位: TULANE UNIVERSITY OF LOUISIANA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-20 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7103498
• 关键词: angiotensin II; arachidonate; blood pressure; cardiovascular surgery; eicosanoid metabolism; enzyme activity; enzyme inhibitors; genetically modified animals; heart catheterization; immunologic assay /test; ionophores; isozymes; laboratory mouse; prostaglandin endoperoxide synthase; prostaglandins; protein structure function; pulmonary artery; pulmonary circulation; pulmonary hypertension; respiratory hypoxia; respiratory surgery; thromboxanes; transfection /expression vector; vascular resistance; vasodilators

DESCRIPTION (provided by applicant): The broad long-term objectives of the proposed research are to improve our current understanding of the regulation of the pulmonary vascular bed by humoral factors, including vasoactive products in the cyclooxygenase pathway. Cyclooxygenase (COX) is the initial step in the formation of prostaglandins (PGs) and thromboxane A2 (prostanoids). The prostanoids have marked effects on the pulmonary vascular bed, and PGI2 is used in the treatment of pulmonary hypertension. It is known that there are two COX isoforms in the lung. COX-1 is believed to be a constitutive enzyme involved in physiologic regulation, whereas COX-2 is an inducible isoform upregulated by inflammatory cytokines. Although it is believed that COX-2 Is not present or expressed in low levels in normal tissue, recent studies in the literature and in our laboratory show that COX-1 and COX-2 are abundantly expressed in the normal healthy rodent lung and have the capacity to generate vasoactive prostanoids from the precursor, arachidonic acid. It is our hypothesis that vasoactive prostanoids that increase pulmonary vascular resistance and decrease systemic vascular resistance are generated by COX-1 and COX-2. The first specific aim is to determine the role of COX-1 and COX-2 in the generation of vasoactive prostanoids in the intact-chest mouse using a recently developed right-heart catheterization procedure to measure pulmonary vascular pressures and blood flow. These studies will involve the use of selective COX-1 and COX-2 inhibitors, a platelet aggregation assay to determine COX-1 selectivity, and enzyme immunoassay to measure prostanoid levels in lung tissue. The second specific aim is to determine the role of COX-1 and COX-2 in the generation of vasoactive prostanoids when arachidonic acid is released from endogenous pools by agents or stimuli reported to release prostaglandins from the lung. In these experiments, the effects of the COX-1 and COX-2 inhibitors on responses to ventilatory hypoxia, angiotensin II, and ionophore A23187 will be investigated in the intact-chest mouse. These experiments will test the hypothesis that responses to ionophore A23187 are mediated by the formation of prostanoids in the COX-1 and COX-2 pathway and that COX-1 and COX-2 modulate pulmonary vasoconstrictor responses to angiotensin II and ventilatory hypoxia. The experiments in specific aims 1 and 2 involve the use of selective COX inhibitors which may be problematic, therefore, specific aim three is to determine the role of COX-1 and COX-2 in the generation of vasoactive prostanoids and in the regulation of the pulmonary vascular bed in COX-1 and COX-2 knockout mice. The results of these experiments will provide new information about the role of COX-1 and COX- 2 in the regulation of the pulmonary vascular bed and may lead to new strategies for the treatment of pulmonary hypertensive disorders.

描述（由申请人提供）：拟议研究的广泛长期目标是提高我们目前对体液因素（包括环氧合酶途径中的血管活性产物）调节肺血管床的理解。环加氧酶 (COX) 是前列腺素 (PG) 和血栓素 A2（前列腺素）形成的第一步。前列腺素类药物对肺血管床有显着影响，PGI2 用于治疗肺动脉高压。已知肺中有两种 COX 同工型。 COX-1被认为是参与生理调节的组成酶，而COX-2是炎症细胞因子上调的诱导型同工型。尽管人们认为 COX-2 在正常组织中不存在或表达水平较低，但文献和我们实验室的最新研究表明，COX-1 和 COX-2 在正常健康啮齿动物肺部大量表达，并且具有从前体花生四烯酸产生血管活性前列腺素的能力。我们的假设是，增加肺血管阻力并降低全身血管阻力的血管活性前列腺素是由 COX-1 和 COX-2 产生的。第一个具体目标是使用最近开发的右心导管插入术测量肺血管压力和血流量，确定 COX-1 和 COX-2 在完整胸部小鼠血管活性前列腺素生成中的作用。这些研究将涉及使用选择性 COX-1 和 COX-2 抑制剂、测定 COX-1 选择性的血小板聚集测定以及测量肺组织中前列腺素水平的酶免疫测定。第二个具体目标是确定当花生四烯酸被报道从肺部释放前列腺素的药物或刺激物从内源性库中释放时，COX-1和COX-2在血管活性前列腺素生成中的作用。在这些实验中，将在完整胸部小鼠中研究 COX-1 和 COX-2 抑制剂对通气缺氧、血管紧张素 II 和离子载体 A23187 反应的影响。这些实验将检验以下假设：对离子载体 A23187 的反应是由 COX-1 和 COX-2 途径中前列腺素的形成介导的，并且 COX-1 和 COX-2 调节肺血管收缩剂对血管紧张素 II 和通气性缺氧的反应。具体目标1和2的实验涉及使用选择性COX抑制剂，这可能存在问题，因此，具体目标3是确定COX-1和COX-2在COX-1和COX-2敲除小鼠中血管活性前列腺素的生成和肺血管床调节中的作用。这些实验的结果将提供关于COX-1和COX-2在肺血管床调节中的作用的新信息，并可能导致治疗肺动脉高压疾病的新策略。