Purkinje Origin of Ischemic Ventricular Tachycardia and Fibrillation

缺血性室性心动过速和颤动的浦肯野起源

• 批准号: 8397522
• 负责人: James B Martins
• 金额: --
• 依托单位: IOWA CITY 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 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8397522
• 关键词: 3-Dimensional; Ablation; Acute; Acute myocardial infarction; Analysis of Variance; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensins; Animal Genetics; Animal Model; Animals; Anterior Descending Coronary Artery; Anti-Arrhythmia Agents; Antioxidants; Arrhythmia; Biological Assay; Ca(2+)-Calmodulin Dependent Protein Kinase; Calcium; Calcium/calmodulin-dependent protein kinase; Canis familiaris; Cell membrane; Cell physiology; Clinical; Clinical Trials; Clonidine; Coronary Occlusions; Coronary heart disease; Data; Enzymes; Exposure to; Fluorescence; Frequencies; Funding; Genetic Models; Goals; Grant; Hand; Hour; Human; In Vitro; Intervention; Investigation; Ischemia; Laboratories; Link; Lovastatin; Lucigenin; Maps; Measurement; Measures; Membrane Potentials; Methods; Microelectrodes; Mitochondria; Modeling; Myocardial Ischemia; NADH oxidase; NADPH Oxidase; Needles; Oxidants; Oxidoreductase; Oxypurinol; Paper; Pathway interactions; Patients; Pharmaceutical Preparations; Prevention; Production; Protocols documentation; Public Health; Reactive Oxygen Species; Research; Risk; Rotenone; RyR2; SERCA2a; Signal Transduction; Source; Stimulus; Sudden Death; System; Techniques; Testing; Tissues; Translations; Ventricular Fibrillation; Ventricular Tachycardia; Veterans; Work; Xanthine Oxidase; acetovanillone; base; calmodulin-dependent protein kinase II; clinical application; clinically relevant; computerized; dihydroethidium; diphenyleneiodonium; effective therapy; enzyme pathway; heart rhythm; improved; in vivo; inhibitor/antagonist; phospholamban; prevent; public health relevance; receptor; research study; sudden cardiac death

DESCRIPTION (provided by applicant): The aim of this project is to continue mechanistic investigation of a canine model of acute myocardial ischemia. This is a remarkably stable model of inducible ventricular tachycardia (VT) and ventricular fibrillation (VF); focal endocardial or Purkinje VT results in half of the experiments and epicardial reentry in the other. Tissue excised from the endocardial focus is studied in vitro with pacing protocols generating cellular calcium based oscillations termed delayed afterdepolarization (DADs) giving rise to an arrhythmia called triggered activity (TA). Clinical laboratories have confirmed focal VT by recording endocardial signals at the origin of VT and VF in patients with acute myocardial ischemia. Moreover, prevention of focal VT/VF with point source endocardial ablation has been proven. Thus this model is a relevant model for human ischemic VT, which may be either focal or reentry. Experiments from the prior funding period have shown that focal endocardial VT is prevented with agents which also prevent TA, including HMG co-A reductase inhibitors (statins) and PD123319 (angiotensin AT-2 receptor antagonist.) Furthermore the effect of statins may result from inhibition of reactive oxygen species (ROS) since a ROS scavenger called TEMPO blocks both VT and TA in a similar manner while decreasing tissue measurements of ROS. ROS may also result in oxidized calcium calmodulin kinase II (CaMKII), a fundamental contributor to VT/VF including reentry in small and large animal models. The overall aim is to test the hypothesis that ROS linked to oxidized CaMKII are basic mechanisms resulting in focal and reentrant VT/VF in a clinically relevant canine model of VT/VF. Investigation centers on two specific aims. Aim 1: Determine whether the highest levels of the ischemic tissue ROS occur at foci of VT/VF and whether decreasing ROS by the scavenger TEMPOL or by inhibition of various enzyme systems that promote ROS including NADH oxidase, mitochondrial or xanthine oxidase more effectively prevents VT/VF. Aim 2: Determine whether the highest levels of oxidized CaMKII activity occur at the foci of VT/VF and if CaMKII inhibition by KN-93 or KN-92 can prevent ischemic focal VT/VF. In vivo computerized activation mapping of multiple transmural bipolar electrograms incorporating Purkinje signals taken from 16 pole needles placed in the risk zone of the anterior descending coronary artery allow 3-D maps of VT/VF produced by extra-stimuli after coronary occlusion. Drugs to be infused to block VT/VF include TEMPO (30 mg/kg,) apocynin (4 mg/kg,) diphenyleneiodine (7.6 mg/kg,) rotenone (9.5 mg/kg,) oxipurinol (3.7 mg/kg,) KN-93 (0.2 <g/kg,) KN-92 (0.2 <g/kg) administered randomly. After activation mapping, tissue at the mechanistic origin of VTVF will be excised for measurements of ROS, CaMKII, RyR2, phospholamban, SERCA2a, and NCX and in vitro microelectrode testing. All the techniques required for these studies are in hand in the laboratories where this preliminary work was done. These studies will utilize Fishers exact test and analysis of variance for quantitative data. Standard microelectrode technique and tissue assays will fulfill the aims. The ultimate goal will be to develop new, effective therapies to prevent ischemic VT/VF in patients with coronary disease, particularly in Veterans.

描述（由申请人提供）： 本课题的目的是继续研究犬急性心肌缺血模型的机制。这是一个非常稳定的诱导室性心动过速（VT）和室颤（VF）的模型;局灶性心内膜异位症或浦肯野室性心动过速的结果在一半的实验和心外膜折返在其他。在体外研究了从内膜病灶切除的组织，起搏方案产生称为延迟后去极化（DAD）的细胞钙基振荡，引起称为触发活动（TA）的心律失常。临床实验室已通过记录急性心肌缺血患者VT和VF起源处的内皮素信号证实了局灶性VT。此外，点源腔内消融可预防局灶性VT/VF。因此，该模型是人类缺血性VT的相关模型，其可以是局灶性的或折返性的。前一个资助期的实验表明，局灶性血管内血栓性室性心动过速可以通过同时预防TA的药物来预防，包括HMG co-A还原酶抑制剂（他汀类药物）和PD 123319（血管紧张素AT-2受体拮抗剂）。此外，他汀类药物的作用可能是由于活性氧（ROS）的抑制，因为称为克里思的ROS清除剂以类似的方式阻断VT和TA，同时降低ROS的组织测量值。ROS也可能导致氧化钙钙调蛋白激酶II（CaMKII），这是小型和大型动物模型中VT/VF（包括折返）的基本促成因素。总体目的是检验与氧化CaMKII相关的ROS是导致临床相关犬VT/VF模型中局灶性和折返性VT/VF的基本机制的假设。调查集中于两个具体目标。目标1：确定最高水平的缺血组织ROS是否发生在VT/VF病灶处，以及通过清除剂TEMPOL或通过抑制促进ROS的各种酶系统（包括NADH氧化酶、线粒体或黄嘌呤氧化酶）来降低ROS是否能更有效地预防VT/VF。目标二：确定最高水平的氧化CaMKII活性是否发生在VT/VF病灶处，以及KN-93或KN-92抑制CaMKII是否可以预防缺血性局灶性VT/VF。多个透壁双极电描记图的体内计算机化激活标测结合从放置在冠状动脉前降支风险区的16极针获取的浦肯野信号，允许冠状动脉闭塞后由额外刺激产生的VT/VF的3-D标测。随机输注克里思（30 mg/kg）、夹竹桃素（4 mg/kg）、二苯碘（7.6 mg/kg）、鱼藤酮（9.5 mg/kg）、奥昔嘌呤醇（3.7 mg/kg）、KN-93（0.2 g/kg）、KN-92（0.2 g/kg）阻断VT/VF。在激活标测后，将切除VTVF机制起源处的组织，用于测量ROS、CaMKII、RyR 2、受磷蛋白、SERCA 2a和NCX以及体外微电极测试。这些研究所需的所有技术都掌握在进行这项初步工作的实验室里。这些研究将使用Fisher精确检验和方差分析进行定量数据。标准的微电极技术和组织分析将实现这一目标。最终目标将是开发新的，有效的治疗方法，以预防冠心病患者，特别是退伍军人的缺血性VT/VF。