CARDIOPULMONARY SURGERY RESEARCH

描述(申请人提供)：拟议研究的广泛的长期目标是提高我们目前对体液因素对肺血管床调节的理解，包括环氧合酶途径中的血管活性产物。环氧合酶(COX)是前列腺素(PGs)和血栓素A2(前列腺素A2)形成的第一步。前列环素对肺血管床有明显的作用，前列腺素I2用于治疗肺动脉高压。已知在肺中有两种COX亚型。COX-1被认为是参与生理调节的构成酶，而COX-2是炎性细胞因子上调的诱导型异构体。虽然人们认为COX-2在正常组织中不存在或低水平表达，但最近的文献和我们实验室的研究表明，COX-1和COX-2在正常健康的啮齿动物肺中大量表达，并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，血管活性前列腺素增加肺血管阻力和降低全身血管阻力是由COX-1和COX-2产生的。第一个具体目的是确定COX-1和COX-2在完整胸腔小鼠血管活性前列腺素生成中的作用，该方法使用最近开发的右心插管程序来测量肺血管压力和血流量。这些研究将涉及选择性COX-1和COX-2抑制剂的使用，用于确定COX-1选择性的血小板聚集法，以及用于测量肺组织中前列腺素水平的酶免疫法。第二个特异性目的是确定环氧合酶-1和环氧合酶-2在花生四烯酸从内生池释放时在血管活性前列腺素生成中的作用。在这些实验中，将研究COX-1和COX-2抑制剂对通气性低氧、血管紧张素II和离子载体A23187反应的影响。这些实验将验证这样一种假设，即对离子载体A23187的反应是通过COX-1和COX-2途径中前列腺素的形成，以及COX-1和COX-2调节对血管紧张素II和呼吸性低氧的肺血管收缩反应。在特定目标1和2中的实验涉及选择性COX抑制剂的使用，这可能是有问题的，因此，特定目标3是确定COX-1和COX-2在COX-1和COX-2基因敲除小鼠血管活性前列腺素生成和肺血管床调节中的作用。这些实验结果将为COX-1和COX-2在肺血管床调节中的作用提供新的信息，并可能为治疗肺动脉高压疾病提供新的策略。

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.