Calcium Regulation in Heart Failure with Preserved versus Reduced Ejection Fraction

项目摘要/摘要 尽管心衰并保留射血分数(HFpEF)占心力衰竭患者心力衰竭的50%。 在美国，没有有效的治疗方法来治疗这种疾病，这与降低射血分数(HFrEF)的心衰形成对比。 同样，尽管对HFrEF中钙调节和兴奋-收缩(EC)耦合的研究已经导致了重要的 改善收缩功能和减少心律失常的治疗方法，对于HFpEF就不能这么说了。匮乏 对HFpEF中钙调节的基本了解是发展Rational的主要障碍 以及对人类这种疾病的有效治疗。我们建议使用Dahl盐敏感(DS)大鼠模型 高血压引起的HFpEF，表现出人类HFpEF的主要血流动力学和临床特征，TO 识别和研究细胞钙调节、EC偶联和肌丝钙反应的不同特征， 它们会影响收缩、舒张期放松和节律。结果将与互补的大鼠进行比较 脑梗塞后血管紧张素转换酶模型。我们的目标是测试钙调节异常的总体假设，而不是 先前在表型验证的HFpEF大鼠模型中证明，不仅与HFrEF不同，而且 共同导致血流动力学和电生理异常，这是HFpEF的特征。我们 有三个目标：目标1：HFpEF与HFrEF的EC偶联和收缩：在这个目标中，我们将使用膜片钳 和钙动力学的同步共聚焦成像，以验证钙诱导的钙释放(CICR)是 通过改变特定的钙调节离子通道和转运体的活性显著增强HFpEF 驻留在心脏偶联，包括钙和钠通道、钠钙交换(NCX)和兰尼定 感受器。目的2：HFpEF和HFrEF的舒张期钙和心室舒张性：我们将测试整体 假设HFpEF舒张期钙调节的关键异常，即肌浆网钙再摄取缺陷和NCX 钙外流仅在β-肾上腺素能刺激时明显，而静息状态下钙摄取异常。我们 将使用实时共聚焦成像来剖析钙摄取机制(例如，SERCA)和挤出(例如， NCX)在钙瞬变的下降阶段，并评估翻译后修饰的效果 由我们的蛋白质组学筛查确定。肌丝分析将揭示钙结合的变化程度 属性和力的产生与被动刚度相比，会导致异常松弛。目标3：骚乱 HFpEF与HFrEF的房室节律比较：使用植入式遥测仪，全心双电压 和钙标测，以及单个窦房结(SAN)细胞膜片钳，我们将检验这一假设 钙调节异常在HFpEF变时性功能不全和心律失常中起重要作用。我们会 我们的研究重点放在下一代RNA测序显示的SAN基因表达变化的作用上。在……里面 结论：本项目将提供一个更深入的理解钙调节之间的差异。 HFpEF和HFrEF，可以基于该实体独特的细胞生理产生新的HFpEF疗法。

PROJECT SUMMARY/ABSTRACT Despite the fact that Heart Failure with Preserved Ejection Fraction (HFpEF) accounts for >50% of HF in the U.S., there are no effective therapies for this disease, in contrast to HF with Reduced Ejection Fraction (HFrEF). Similarly, while studies of Ca regulation and excitation-contraction (EC) coupling in HFrEF have led to important therapies to improve contractile function and reduce arrhythmia, the same cannot be said for HFpEF. The lack of fundamental understanding of Ca regulation in HFpEF is a major impediment to the development of rational and effective therapies for this disease in humans. We propose to use the Dahl Salt-sensitive (DS) rat model of hypertension-induced HFpEF, which exhibits the major hemodynamic and clinical features of human HFpEF, to identify and investigate distinctive features of cellular Ca regulation, EC coupling and myofilament Ca response, which influence contractility, diastolic relaxation and rhythm. Results will be compared with a complementary rat model of post-infarction HFrEF. Our goal is to test the overall hypothesis that abnormalities in Ca regulation, not previously demonstrated in a phenotypically-verified HFpEF rat model, are not only distinct from HFrEF but also collectively contribute to the hemodynamic and electrophysiological abnormalities that characterize HFpEF. We have three aims: Aim 1: EC Coupling & Contractility in HFpEF vs HFrEF: In this aim, we will use patch clamp and simultaneous confocal imaging of Ca dynamics to test the hypothesis that Ca-induced Ca release (CICR) is markedly enhanced in HFpEF by changes in the activity of specific Ca-regulating ion channels and transporters residing in the cardiac couplon, including Ca and Na channels, sodium-calcium exchange (NCX) and ryanodine receptors. Aim 2: Diastolic Calcium & Ventricular Relaxation in HFpEF vs HFrEF: We will test the overall hypothesis that the key abnormality of diastolic Ca regulation in HFpEF, i.e. defective SR Ca reuptake and NCX Ca efflux, is only apparent upon β-adrenergic stimulation, whereas Ca uptake is abnormal at rest in HFrEF. We will use live confocal imaging to dissect the role of Ca uptake mechanisms (e.g. SERCA) and extrusion (e.g. NCX) in the declining phase of the Ca transient, and assess the effects of posttranslational modifications identified by our proteomics screen. Myofilament assays will reveal the extent whereby changes in Ca binding properties and force generation versus passive stiffness contribute to abnormal relaxation. Aim 3: Disturbances of Atrial & Ventricular Rhythm in HFpEF vs HFrEF: Using implantable telemeters, whole heart dual voltage and calcium mapping, and single sinoatrial node (SAN) cell patch clamp, we will test the hypothesis that abnormal Ca regulation plays a critical role in chronotropic incompetence and arrhythmia in HFpEF. We will focus our studies on the role of altered SAN gene expression indicated by next generation RNA sequencing. In conclusion, this project will provide an advanced understanding of the differences between Ca regulation in HFpEF and HFrEF that may generate novel HFpEF therapies based on that entity’s unique cellular physiology.