Surgical Revascularization's Impact on Mitochondria in Hibernating Myocardium

血运重建手术对冬眠心肌线粒体的影响

• 批准号: 8043456
• 负责人: Rosemary Frances Kelly
• 金额: --
• 依托单位: MINNEAPOLIS VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8043456
• 关键词: Animal Model; Animals; Anterior; Apoptosis; Area; Arteries; Bioenergetics; Blood; Blood flow; Bypass; Cardiac; Cardiopulmonary Bypass; Carrier Proteins; Chest Pain; Chronic; Clinical; Complex; Computers; Control Groups; Coronary; Coronary artery; Defect; Dobutamine; Dose; Echocardiography; Electron Transport; Energy Metabolism; Ensure; Equilibrium; Experimental Models; Failure; Family suidae; Global Change; Goals; Heart; Heart failure; Hibernation; Hypoxia; Individual; Infarction; Injury; Ischemia; Left; Measures; Metabolism; Methods; Microspheres; Mitochondria; Mitochondrial Proteins; Modeling; Muscle Cells; Myocardial; Myocardial Infarction; Myocardial Ischemia; Myocardial tissue; Myocardium; Necrosis; Operative Surgical Procedures; Outcome; Oxygen; Oxygen Consumption; Patients; Perfusion; Physiological; Positioning Attribute; Proteins; Proteomics; Pump; Recovery; Recovery of Function; Regional Blood Flow; Relative (related person); Research; Rest; Spasm; Stress; Study models; Techniques; Testing; Thrombosis; Time; Tissue Survival; Tissues; Western Blotting; Work; Workload; deprivation; design; detector; heart cell; high risk; improved; injured; internal thoracic artery; novel; oligomycin sensitivity-conferring protein; operation; protein expression; response; restoration; revascularization surgery; success; tomography

DESCRIPTION (provided by applicant): Background: Hibernating myocardium is viable, persistently dysfunctional myocardium that occurs in response to continuing or repetitive myocardial ischemia and is characterized by hypoperfusion without evidence of necrosis. Our group has successfully established a reproducible swine model of hibernating myocardium and has studied this model extensively. As an extension of this work, we have now established a novel method whereby (a) we perform off-pump single vessel bypass surgery with survival to revascularize ischemic myocardium and (b) we test the success of such surgery in recovering myocardial function using physiologic and proteomic approaches. Surgical revascularization of chronically ischemic myocardium with survival has never been studied in an animal model and so it has significant implications in understanding heart failure and the potential for recovery. Methods: In a swine model of hibernating myocardium, surgical revascularization (vesus sham operation) will be performed using the left internal mammary artery to bypass the chronically obstructed left anterior descending artery using a beating heart, off-pump technique, which is identical to the clinical technique. At 12 and 20 weeks, a prebypass and postbypass multi-detector computer tomography (MDCT) and transthoracic echocardiogram (TTE) in both groups will be obtained to determine LIMA patency, recovery of regional wall thickening, and recovery of subendocardial perfusion. Also, studies of the recovery induced by surgical revascularization of hibernating myocardial blood flow, mitochondrial bioenergetics and protein alterations are simultaneous analyzed at the terminal study to more accurately understand the spectrum of myocardial functional recovery. Proteomic mitochondrial responses following revascularization will be compared to the control group of chronic ischemia (hibernation) using, western blot analysis and proteomic analysis [isobaric Tags for Relative and Absolute Quantification (iTRAQ)]. Aims: The aim of this study is to understand the changes that are induced upon the hibernating myocardium of the swine model when it is successfully surgically revascularized. In this model we will evaluate whether surgical revascularization normalizes regional blood flow at rest and with increased work load (dobutamine stress) by measuring blood flow (microsphere analysis) and cardiac function (2D ECHO, MDCT). A second aim is to understand the alteration in the oxygen consumption of the hibernating myocardium following revascularization. We will evaluate this aim by comparing the bioenergic state of the revascularized myocardium to the hibernating myocardium, quantifying the proteomic changes in the mitochondria of both groups and evaluating enzymatic protein activity as directed by the proteomic changes. Conclusion: Clinical understanding of potential recovery of hibernating myocardium is limited by the lack of an appropriate animal model to identify and test alleged markers predicting benefit with surgery. Adaptations to hibernation are complex and involve alterations in the bioenergetics and proteomics of the mitochondria that allow the tissue to maintain its viability while sacrificing myocardial function. Hibernating myocardium appears to have dynamic proteomic responses to persistent ischemic stress, which has similarities to the global changes in energy substrate metabolism and function seen in advanced heart failure. These proteomic changes may limit oxidative injury and apoptosis and impact functional recovery after revascularization. We believe that hibernating myocardium is an adaptation to promote survival but at the expense of contractility. Clinically, revascularization of hibernating myocardium results in a wide spectrum of outcomes from near total recovery of function to dense infarction. The mechanisms of hibernating myocardium to restore complete and reliable myocardial function and mitochondrial bioenergetics following the reestablishing blood flow through coronary revascularization remain unknown and require study. PUBLIC HEALTH RELEVANCE: Patients with episodic chest pain prior to a heart attack suffer less damage to the heart than individuals presenting with the same type of heart attack but without prior warning attacks. The warning attacks, called angina, indicate that the heart is transiently stressed by increased work load demands, by spasm or fluctuating thrombosis in one of the arteries prior to its complete closure. These periods of increased demand or of decreased blood flow stimulate the heart to adapt favorably to a more prolonged episode of oxygen deprivation. This concept, referred to as the "smart heart," relies on alterations in the energy producing parts of the heart cells, the mitochondria. We propose that mitochondria in chronically ischemic heart cells have acquired protection against low blood flow. By performing a surgical operation to resupply blood to the heart, our research will test whether these adaptations to ischemia are reversible and allow the heart to return to normal function, or if the adaptations are permanent.

描述（由申请人提供）： 背景资料：冬眠心肌是存活的、持续性功能障碍的心肌，其发生是对持续或重复心肌缺血的反应，其特征是灌注不足而无坏死证据。本课题组成功地建立了一种可重复的猪冬眠心肌模型，并对该模型进行了广泛的研究。作为这项工作的延伸，我们现在已经建立了一种新的方法，即（a）我们进行非体外循环单血管旁路手术，存活缺血心肌血运重建和（B）我们测试这种手术的成功，在恢复心肌功能的生理和蛋白质组学方法。慢性缺血心肌的手术血运重建与存活从未在动物模型中进行过研究，因此它对理解心力衰竭和恢复潜力具有重要意义。研究方法：在冬眠心肌的猪模型中，将使用与临床技术相同的心脏不停跳、非体外循环技术，使用左乳内动脉进行外科血运重建（vesus假手术），以绕过慢性阻塞的左前降支动脉。在第12周和第20周，将获得两组的旁路手术前和旁路手术后多探测器计算机断层扫描（MDCT）和经胸超声心动图（TTE），以确定LIMA通畅性、局部壁增厚的恢复情况和内膜下灌注的恢复情况。此外，在终末研究中同时分析了冬眠心肌血流量、线粒体生物能量学和蛋白质改变的手术血运重建诱导的恢复研究，以更准确地了解心肌功能恢复的谱。将使用蛋白质印迹分析和蛋白质组学分析[相对和绝对定量的同量异位素标签（iTRAQ）]将血运重建后的蛋白质组线粒体反应与慢性缺血（冬眠）对照组进行比较。目的：本研究的目的是了解冬眠心肌的猪模型，当它成功地手术血运重建诱导的变化。在该模型中，我们将通过测量血流量（微球分析）和心脏功能（2D ECHO，MDCT）来评估手术血运重建是否使静息时和工作负荷增加（多巴酚丁胺负荷）时的局部血流量正常化。第二个目的是了解血运重建后冬眠心肌耗氧量的变化。我们将通过比较血运重建心肌与冬眠心肌的生物能量状态，定量两组线粒体中的蛋白质组学变化，并根据蛋白质组学变化评估酶蛋白活性来评估这一目标。结论：由于缺乏合适的动物模型来识别和测试所谓的预测手术获益的标志物，对冬眠心肌潜在恢复的临床理解受到限制。适应冬眠是复杂的，涉及线粒体的生物能量学和蛋白质组学的改变，使组织在牺牲心肌功能的同时保持其活力。冬眠心肌似乎对持续缺血应激有动态蛋白质组学反应，这与晚期心力衰竭中能量底物代谢和功能的整体变化相似。这些蛋白质组学变化可能限制氧化损伤和细胞凋亡，并影响血运重建后的功能恢复。我们认为，冬眠心肌是一种适应，以促进生存，但在收缩力的代价。临床上，冬眠心肌的血运重建可导致广泛的结局，从功能几乎完全恢复到致密梗死。冬眠心肌通过冠状动脉血运重建重建血流后恢复完整和可靠的心肌功能和线粒体生物能量学的机制仍然未知，需要研究。 公共卫生关系： 在心脏病发作前有阵发性胸痛的患者，其心脏受到的损害比有相同类型心脏病发作但没有预先警告发作的患者要小。警告发作，称为心绞痛，表明心脏是短暂的压力增加的工作负荷的要求，痉挛或波动血栓形成之前，在其完全关闭的动脉之一。这些需求增加或血流量减少的时期刺激心脏有利地适应更长时间的缺氧。这个概念，被称为“智能心脏”，依赖于心脏细胞中产生能量的部分线粒体的改变。我们认为慢性缺血性心脏细胞中的线粒体已经获得了对低血流量的保护。通过进行外科手术为心脏补充血液，我们的研究将测试这些对缺血的适应是否是可逆的，并允许心脏恢复正常功能，或者这些适应是否是永久性的。