Relationship between early and late events in the cardiac cycle as control points for therapeutic intervention

心力衰竭是全世界致残和死亡的主要原因，大约50%的心力衰竭相关死亡是突然的，可能是由心脏电信号异常（心律失常）引起的。与一般人群相比，心力衰竭患者心脏性猝死的风险增加了6- 9倍。根据“英格兰心脏筛查研究”，心力衰竭患者的死亡风险为每年9%，50岁以上人群的患病率约为6.6%（并且随着年龄的增长而迅速增加）。在这项研究中，我们将研究心脏细胞中电信号和钙代谢之间的相互关系，特别强调理解细胞信号传导的综合方法。有充分的证据表明，心力衰竭与细胞内钙信号的变化有关，钙信号不仅控制收缩力（以及心脏泵血的能力），还影响电活动。心脏的收缩，在心力衰竭中受到损害，是由一个电信号引起的它导致钙被释放到细胞内钙信号的时间过程和振幅是收缩力的主要决定因素。然而，信号不是单向的，因为钙也会影响电活动，特别是当细胞在下一次跳动之前必须将其电压恢复到正常水平时。我们的目标是通过药物和/或通过操纵细胞中的关键蛋白表达来优化电和钙信号所需的科学理解。使用生物物理技术，我们将研究细胞如何响应控制心脏细胞电压的蛋白质表达的测量变化，以及这些变化如何影响细胞中发生的后期电和钙信号事件。使用药理学试剂，我们将剖析正常和异常电活动的电原因，以及它们是如何被钙信号的变化所调节的。同时，我们将探索电压变化如何影响钙信号传导机制，通过使用计算机产生的电流并将其输入细胞来打破钙信号传导和电流之间的反馈回路，以便进行分析。所有的数据都将被整合到计算机模型中，使我们能够重新整合和测试我们对电和钙信号变化如何共同作用以导致疾病状态的理解。在这一点上，我们将能够确定如何使用药物混合物来提高收缩强度，同时最大限度地降低心律失常的风险。我们还知道，由于细胞结构的微观解剖变化，心脏细胞膜和细胞内钙储存之间的信号通路可能会被破坏。目前尚不清楚心脏细胞如何适应这些变化，尽管我们知道细胞内钙储存释放系统变得更加“泄漏”。利用细胞内一种新型的照明形式（即双光子激发的闪光光解）和可以对照明做出反应的特殊分子，我们将探索钙储存的微观元素如何响应我们人工生成的触发信号。这将揭示这种亚细胞问题的程度，从而确定开发新的治疗药物以改善钙储存泄漏释放的效用。我们还将研究亚细胞信号转导系统/途径如何影响系统的综合反应，以进一步完善衰竭心脏中有缺陷的电和钙信号系统的可能控制点。

Heart failure is a major cause of disability and death worldwide, and approximately 50% of heart failure-related deaths are sudden and may be explained by abnormal electrical signals in the heart (arrhythmias). Heart failure patients have a 6- to 9-fold increased risk of sudden cardiac death compared to the general population. According to the "Heart of England screening study" the mortality risk for heart failure patients is 9% per year with a prevalence of ~6.6% of the population at 50 years of age (and which increases rapidly with age). In this study we will examine the interrelationships between electrical signals and calcium metabolism in heart cells with special emphasis on an integrative approach to understanding cell signalling. There is good evidence that heart failure is linked to changes in calcium signalling within cells which not only controls the force of contraction (and the ability of the heart to pump blood) but also affects electrical activity. The contraction of the heart, which is compromised in heart failure, is initiated by an electrical signal which causes calcium to be released inside the cell and it is the time course and amplitude of this calcium signal which is a major determinant of contraction force. However, the signal is not one way since calcium also affects electrical activity, especially later when the cell has to return its voltage to normal levels before the next beat. Our goal is to develop the scientific understanding needed to optimise both electrical and calcium signalling with drugs and/or by manipulation of key protein expression in the cell.Using biophysical techniques, we will examine how the cell responds to measured changes in the expression of proteins that control heart cell voltage and how these changes affect the later electrical and calcium signalling events that occur in the cell. Using pharmacological agents we will dissect the electrical causes of normal and abnormal electrical activity together with how they are modulated by changes in calcium signalling. At the same time, we will probe how changes in voltage affect the calcium signalling mechanisms by using computer-generated electrical currents and feeding them into the cell to break feedback loops between calcium signalling and electrical currents to allow analysis. All of the data will be incorporated into computer models to allow us to re-integrate and test our understanding of how the electrical and calcium signalling changes work together to contribute to the disease state. At this point we will be able to identify how mixtures of drugs can be used to improve contraction strength while, at the same time, minimise arrhythmia risk.It is also known that signalling pathways between the heart cell surface membrane and the intracellular store of calcium may become disrupted due to micro-anatomical changes in cell structure. It is not clear how heart cells adapt to these changes although we know that the intracellular calcium store release system becomes more 'leaky'. Using a novel form of illumination inside the cell (namely 2-photon excited flash photolysis) with special molecules that can react to the illumination, we will probe how microscopic elements of the calcium store respond to our artificially generated trigger signals. This will reveal the extent of this subcellular problem and therefore identify the utility of developing new therapeutic agents to ameliorate the leaky calcium store release. We will also be examining how subcellular signal transduction systems/pathways affect the integrated response of the system, to further refine possible points of control in the defective electrical and calcium signalling systems in the failing heart.