A full spectrum rational approach to identify antiarrhythmic agents targeting IKs Channels

项目摘要 获得性长Q-T综合征（aLQTS）是由于心电图（EKG）的延长而引起的心电图（EKG）变化。 心室电事件，动作电位（AP）。这种延长的AP容易导致致命的心律失常 突然死亡。aLQTS由FDA批准的许多药物诱导。然而，批准的剂量是 受这种副作用的限制。慢延迟整流器IKs是一种K+电流，可以通过缩短aLQTS来防止aLQTS APD。该提案的重点是开发可以消除APD延长的候选药物 是由导致长QT综合征的药物引起的有5个步骤，调节通道的开放，电压传感器 激活、4，5-二磷酸磷脂酰肌醇（PIP 2）、钙调蛋白、ATP和孔的打开。两 电压传感器激活和PIP 2结合使我们得到了aLQTS的两种候选化合物。 由于许多候选药物由于心脏毒性而失败，因此研究所有机制是重要的 控制通道开放。第一个目的，目的1，研究钙调素和ATP结合和孔 开放可以通过新的试剂刺激以增加IKs。选择的系统过程 这些新的药物被称为全谱合理药物设计。通道的结构是 研究和化合物的结合位点，以修改通道开放的特定步骤， (e.g.,钙调蛋白和ATP相互作用和孔开放）。计算机程序利用这些结构信息 为了筛选一个超过100万种化合物的化学库，寻找那些最有可能结合在细胞周围的化合物， 结构性定义的网站。多种化合物已经被确定为潜在有效的， 从这些化合物中提供了每个潜在地点的初步数据。目的1测试这些化合物， 确定它们对IKs的作用，以及它们的剂量反应曲线和选择性。提出的机制 对每个治疗部位的研究将提供对任何设计为靶向IKs的抗癫痫药物的深入了解。的 第二个目标，目标2，集中在命中剂对离子通道的功能和动作电位的影响， 犬心室和心房肌细胞。目标1中的每种最佳候选药物都将在 IKs的生物物理特性。还将在多个浓度下研究它们的动作电位， 刺激频率，以及在两种对照条件下不存在和存在β激动剂的情况下，以及 延长APD作为药物诱导的aLQT模型的那些。包括心房肌细胞是因为 铅化合物必须不会引起房性心律失常作为安全性测量。

Project Summary Acquired Long Q-T Syndrome (aLQTS) is a change in the electrocardiogram (EKG) due to lengthening of the ventricular electrical event, the action potential (AP). This lengthened AP predisposes to a lethal arrhythmia and sudden death. aLQTS is induced by many drugs approved by the FDA. However, the approved doses are limited by this side effect. The slow delayed rectifier, IKs, is a K+ current that can prevent aLQTS by shortening the APD. This proposal focuses on developing candidate agents that can eliminate the APD prolongation induced by drugs that cause aLQTS. There are 5 steps that regulate opening of the channel, voltage sensor activation, phosphatidylinositol 4,5-biphosphate (PIP2), Calmodulin, ATP and opening of the pore. Two of these, voltage sensor activation and PIP2 binding, have led us to two candidate compounds for aLQTS. Because many drug candidates fail due to cardiac toxicity, it is important to investigate all mechanisms controlling channel opening. The first aim, Aim 1, investigates how calmodulin and ATP binding and pore opening can be stimulated by novel agents to increase IKs. The systematic process by which the selection of these novel agents is achieved is called Full Spectrum Rational Drug Design. The structure of the channel is studied and the binding sites for compounds to modify particular steps in channel opening are determined (e.g., calmodulin and ATP interactions and pore opening). A computer program uses this structural information to screen a chemical library of more than 1 million compounds for those most likely to bind near to the structurally defined site. Multiple compounds have already been identified as potentially effective and preliminary data are provided from these compounds for each potential site. Aim 1 tests these compounds to determine their action on IKs, as well as their dose response curve and selectivity. The proposed mechanistic studies of each therapeutic site will provide insight into any antiarrhythmic drug designed to target IKs. The second aim, Aim 2, focuses on the effects of the hit agents on the ion channel’s function and action potential in canine ventricular and atrial myocytes. Each optimal drug candidate from Aim 1 will be studied on the biophysical properties of IKs. They will also be studied on the action potential at multiple concentrations, frequencies of stimulation, and in the absence and presence of a β agonist in both control conditions, and those that prolong the APD as a model for drug induced aLQTs. Atrial myocytes are included because the lead compound must not cause atrial arrhythmias as a measurement for safety.