Surgical Cardioprotection Through BKCa-Dependent Modulation of Mitochondrial Supercomplexes

摘要：与择期心脏骤停相关的缺血性损伤后出现心肌顿抑 在大多数心脏手术期间，并极大地增加了患者的发病率和死亡率。在.期间 外科手术，心脏停搏液提供了显著的心脏保护，否则将是致命的 缺血性损伤。然而，在这些手术过程中，仍然存在对心肌组织的重大损伤。这 格兰特试图确定1)与线粒体K激活相关的心脏保护机制 通道(BKCa)和IF驱动激活将减轻与缺血损伤相关的心肌顿抑 在心脏手术期间，以及2)促进线粒体重组和功能的新策略 可行的治疗策略。线粒体K介导的心肌保护机制目前 未知。我们提供了初步的数据，激活剂或过度表达活性的BKCa通道可以改善LV 与分离细胞和动物模型相关的缺血性损伤后的功能和血流动力学 心脏停搏。我们还提出了激活BKCa可能改善心脏保护的新证据。 通过改变线粒体结构蛋白，增加电子传递链的形成 超复合体，从而提供更有效的细胞呼吸，并减少活性氧物种 一代。目前的建议将研究线粒体K介导的新机制 线粒体脊连接蛋白K依赖性调控对心肌的保护作用 促进线粒体超复合体的形成，改善呼吸作用，降低ROS。在……里面 此外，正在大力翻译这些研究报告，并在#中核实了相关结论。 临床前CPB/CPB大动物模型的建立及其对人心脏病理损伤的定义 心脏手术前后的组织。对这一机制的潜在阐明将对 缺血性损伤和许多其他心肌代谢改变。该提案有三个具体目标：i) 确定呼吸超复合体和肋骨重塑在BKCa介导的增强中的作用 体外心肌保护。BKCa介导的心脏保护(呼吸、呼吸)机制 超络合物形成、三磷酸腺苷生成、超氧化物生成等)将使用独立的 心肌细胞的遗传和药物操作。Ii)确定BKCa介导的超复合体 心脏停搏后形成增强心脏收缩功能和心脏保护 体外再灌流。小鼠离体心将受到缺血停搏和再灌注的影响 使用和不使用BKCa通道、药理激活剂和遗传干预。三)确定是否类似 在使用心肌组织样本进行CP/CPB的人中存在病理机制 和旁路后，最后确定BKCa激活是否促进了超复杂格式并减少了 临床相关的CP/CPB大型动物模型心肌顿抑。

Abstract: Myocardial stunning is present following ischemic insults associated with elective cardiac arrest during the majority of cardiac surgeries and significantly contributes to patient morbidity and mortality. During surgery, cardioplegia solutions provide significant cardioprotection from what would otherwise be lethal ischemic injury. However, there is still significant injury during these procedures to the myocardial tissue. This grant seeks to determine 1) the mechanism of cardioprotection associated with activation of a mitochondrial K+ channel (BKCa) and if driving activation will mitigate myocardial stunning associated with ischemic insults during cardiac surgery, and 2) if novel strategies to promote mitochondrial reorganization and function are viable therapeutic strategies. The mechanism of mitochondrial K+-mediated cardioprotection is currently unknown. We present preliminary data, that activators or overexpression of active BKCa channels improves LV function and hemodynamics following ischemic injury associated with isolated cell and animal models of cardioplegic arrest. We also present novel evidence that BKCa activation may improve cardioprotection through alterations in mitochondrial structural proteins and increase the formation of electron transport chain supercomplexes, thereby providing more efficient cellular respiration, and decreased reactive oxygen species generation. The current proposal will investigate the novel mechanism of mitochondrial K+ mediated cardioprotection with specific focus on K+-dependent modulation of mitochondrial cristae junction protein complexes, enhanced mitochondrial supercomplex formation, improved respiration, and decreased ROS. In addition, there is a strong effort towards translation of these studies, with verification of the relevant findings in a pre-clinical large animal model of CP/CPB and definition of the proposed pathological insult in human heart tissue before and after cardiac surgery. The potential elucidation of this mechanism will have implication for ischemic injury and numerous other myocardial metabolic alterations. The proposal is in three specific aims: I) Determine the role of respiratory supercomplexes and cristae remodeling in BKCa-mediated enhanced myocardial protection in vitro. The mechanism of BKCa-mediated cardioprotection (respiration, respiratory supercomplex formation, ATP generation, superoxide production, etc...) will be evaluated using isolated myocytes with genetic and pharmacologic manipulation. II) Determine if BKCa-mediated supercomplex formation enhances cardiac contractile function and cardioprotection following cardioplegic arrest and reperfusion ex vivo. Mouse isolated hearts will be subjected to ischemic cardioplegic arrest and reperfusion with and without BKCa channel pharmacologic activators and genetic interventions. III) Determine if similar pathological mechanisms are present in humans undergoing CP/CPB using myocardial tissue samples before and after bypass, and finally, determine if BKCa activation promotes supercomplex formaton and reduces myocardial stunning in a clinically relevant diseased large animal model of CP/CPB.