Nitric Oxide/Carbon Monoxide in Pulmonary Hypertention

描述(由申请人提供)： 我们已经证明，原发性肺动脉高压(PPH)患者呼气中的一氧化氮(NO)水平较低，这表明NO在肺动脉高压的病理生理机制中发挥了作用。本研究旨在探讨PPH患者体内NO水平降低的机制(S)。将在实验中解决的潜在机制是CO抑制NO的产生，以及影响NO合成酶(NOS)对氧的敏感性的酶动力学异常。我们以前已经证明，生理范围内的氧浓度决定了肺中NO合成的速度。然而，尽管接受了补充氧疗，PPH患者的NO水平仍然很低。这表明PPH中的NO合成酶可能对氧不那么敏感，因此需要比正常氧更高的氧来产生NO。此外，CO还可以直接影响内源性NO的合成。在初步数据中，PPH中的CO处于可能导致NOS活性抑制和NO生成的范围内。我们推测，在PPH中，NO的减少可能是由于高CO水平和/或削弱了对氧气的反应而产生的NO。作为这一假设的延伸，我们还提出了有效的治疗方法，如Epoprotenol，可能部分通过增加PPH中的NO水平起作用。为了验证这一假设，我们提出了以下具体目标：目的1.确定PPH患者一氧化碳(CO)水平与NO和疾病严重程度的关系。目的2.研究氧气和环前列烯醇对PPH大鼠体内NO水平的影响。目的3.体外研究02和CO对一氧化氮合酶(NOS)表达和活性的影响。正规课程工作和教育被纳入本提案的培训部分。候选人将通过一个指导小组得到肺生物学和肺动脉高压领域领导人的指导。通过五年奖，候选人将在(I)以假设为导向的研究设计，(Ii)数据的分析和解释，以及(Iii)手稿、摘要的写作和在会议上展示数据方面发展他的技能。这项提议的培训部分将导致候选人向完全独立的调查员过渡。

DESCRIPTION (provided by applicant): We have shown that patients with primary pulmonary hypertension (PPH) have low levels of nitric oxide (NO), a potent vasodilator, in exhaled breath suggesting a role for NO in the pathophysiology of pulmonary hypertension. The purpose of this proposed research is to determine the mechanism(s) for low NO in PPH. Potential mechanisms that will be addressedin the experiments are inhibition of NO production by CO and enzyme kinetic abnormalities affecting the sensitivity of NO synthase (NOS) to oxygen. We have previously shown that oxygen concentrations in the physiologic range determine the rate of NO synthesis in the lung. However, PPH individuals have low NO despite receiving supplemental oxygen therapy. This suggests that NO synthases in PPH may be less sensitive to oxygen and thus require higher than normal oxygen to produce NO. Furthermore, CO can directly affect endogenous NO synthesis. In preliminary data, CO in PPH is in the range that may lead to inhibition of NOS activity and NO generation. We hypothesize that NO is decreased in PPH perhaps as a consequence of high CO levels and/or impaired NO production in response to oxygen. As an extension of this hypothesis, we also propose that effective therapies such as epoprostenol, may act in part by increasing NO levels in PPH. To test this hypothesis, we propose the following specific aims: Aim 1. Determine the levels of Carbon monoxide (CO) in relationship to NO and severity of disease in PPH. Aim 2. Study the effect of oxygen and epoprostenol on NO levels in PPH in vivo. Aim 3. Study the effect of 02 and CO on NOS expression and activity in vitro. Formal course work and education are incorporated into the training component of this proposal. The candidate will have direction from leaders in the field of lung biology and pulmonary hypertension through a mentoring group. Through the 5 year award, the candidate will develop his skills in (i) hypotheses-driven design of studies, (ii) analyses and interpretation of data, and (iii) writing of manuscripts, abstracts and presenting data at meetings. The training component of this proposal will lead to the candidate's transition to a fully independent investigator.