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

心力衰竭是世界范围内残疾和死亡的主要原因，约50%的心力衰竭相关死亡是突然的，可能由心脏异常电信号（心律失常）解释。与一般人群相比，心力衰竭患者的心源性猝死风险增加6至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岁人群的患病率约为6.6%（且随年龄增长迅速增加）。在这项研究中，我们将研究电信号和钙代谢之间的相互关系，特别强调一个综合的方法来理解细胞信号。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（和心脏泵血的能力），而且影响电活动。在心力衰竭中受损的心脏收缩由导致钙在细胞内释放的电信号启动，并且该钙信号的时间过程和幅度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，特别是当细胞必须在下一次跳动之前将其电压恢复到正常水平时。我们的目标是发展所需的科学理解，以优化电和钙信号与药物和/或通过操纵细胞中的关键蛋白质的表达。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来的电和钙信号事件。我们将使用药理学试剂来剖析正常和异常电活动的电原因，以及它们如何通过钙信号的变化来调节。与此同时，我们将探索电压的变化如何影响钙信号传导机制，方法是使用计算机生成的电流并将其输入细胞，以打破钙信号传导和电流之间的反馈回路，从而进行分析。所有的数据都将被纳入计算机模型，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促进疾病状态的理解。在这一点上，我们将能够确定如何混合药物可以用来提高收缩强度，而在同一时间，最大限度地减少心律失常的风险。它也是已知的，心脏细胞表面膜和细胞内钙储存之间的信号通路可能会成为由于细胞结构的微观解剖变化中断。目前尚不清楚心脏细胞如何适应这些变化，虽然我们知道，细胞内钙储存释放系统变得更加“泄漏”。使用一种新形式的照明细胞内（即双光子激发闪光光解）与特殊的分子，可以对照明反应，我们将探测钙存储的微观元素如何响应我们人工产生的触发信号。这将揭示这种亚细胞问题的程度，并因此确定开发新的治疗剂以改善泄漏的钙储存释放的效用。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.