The Late L-type Ca Current as the Target for a New Class of Antiarrhythmics

项目总结： 这些研究的动机是迫切需要一种新的有效和安全的抗心律失常药物来 在不影响EC耦合的情况下防止VT/VF。CAV通道阻滞剂(IV类抗心律失常药，如 Diltiazem和Verapamil)由于具有负性肌力作用，治疗价值有限。这些 研究人员最近发现，致心律失常的内源性肾上腺素能被最低限度的 L型钙通道生物物理参数的修正。至关重要的是，这些演习的目的是 常见的是它们都降低了L型钙电流的晚期分量(晚期ICa，L)。选择性减量 后期的ICA中，L的好处是离开了ICA的巅峰，L基本完好无损，保持了收缩能力。遗憾的是，虽然 颈内动脉的相关性，L窗电流与EAD的形成是30年前假设的，没有基于 这个想法还没有出现。从研究人员最近的研究中得出的抗心律失常策略 室性心动过速/室性心动过速的动物模型现已准备好用于药理学研究：目标1建议“评估 LTCC门控修饰剂选择性降低后期成分的独立分量分析，L作为新的原型成员 一类不阻断ICa峰的抗心律失常药，L“。具体地说，目标1A将”验证抗心律失常药 应用LTCC门控修饰剂对颈内动脉内支架的潜力进行L复位，并判定飞行员的疗效 选择性降低晚期ICA的化合物，L：罗司可汀对映体，已知能降低ICA，L的底座电流。 Aim 1B将使用LTCC门控验证ICA，L窗电流降低的抗心律失常潜力 修饰语“。加巴喷丁类化合物，在初步研究中发现可以通过移位LTCC来减少ICA，L窗口电流 对去极化电位的电压依赖激活将被用作先导化合物。在成功的基础上 在单细胞和完整心脏的初步研究中，这些药物预防或抑制VT/VF的能力将 在有利于EAD的条件下(氧化应激、低钾血症)在整个兔和大鼠心脏中进行评估。 建立晚期颈内动脉VT/VF的预防效果，L在两个小动物模型上的减少将证明 转化为更大的哺乳动物模型，最终转化为人类。Aim 2，旨在“识别 晚期ICA的分子机制，L被罗可维汀和加巴喷丁还原，原型 潜在的新一类抗心律失常药物的成员“。调查人员将利用他们的 利用电压光学跟踪人类CaV1.2通道分子跃迁的最新突破 钳位荧光法确定先导化合物修饰LTCC以减少延迟的机制 Ica，L.具体地说，Aim 2A将“确定支持底座Ica的分子机制，L通过 Roscovitine和Aim 2B将确定窗口型ICA的分子机制，L通过 加巴喷丁“。这些信息将揭示下一代抗心律失常药物应该如何作用于LTCC。 因此，这一提议有两个主要的新颖方面：它为一个概念上的新类别奠定了基础 抗心律失常药物(LTCC门控调节剂)，并指导未来LTCC分子的合理药物设计。

PROJECT SUMMARY: The motivation for these studies is the pressing need for a new class of effective and safe antiarrhythmics to prevent VT/VF without compromising EC coupling. CaV channel blockers (Class IV antiarrhythmic agents, such as Diltiazem and Verapamil) have limited therapeutic value because of their negative inotropic effect. These investigators have recently discovered that arrhythmogenic EADs are potently suppressed by the minimal modification of the L-type Ca channel biophysical parameters. Crucially, what these maneuvers have in common is that they all reduce the late component of the L-type Ca current (late ICa,L). The selective reduction of late ICa,L has the benefit of leaving peak ICa,L largely intact, preserving contractility. Regrettably, while the relevance of the ICa,L window current to EAD formation was hypothesized 30 years ago, no therapy based on this idea has emerged yet. The antiarrhythmic strategies that emerged from the investigators’ recent studies in animal models of VT/VF are now ready to be pharmacologically implemented: Aim 1 proposes "to evaluate LTCC gating modifiers selectively reducing the late component of ICa,L as prototype members of a new class of antiarrhythmics that do not block peak ICa,L". Specifically, Aim 1A will "validate the antiarrhythmic potential of pedestal ICa,L reduction using LTCC gating modifiers" and determine the efficacy of pilot compounds that selectively decrease late ICa,L: roscovitine enantiomers, known to reduce ICa,L pedestal current. Aim 1B will “validate the antiarrhythmic potential of ICa,L window current reduction using LTCC gating modifiers”. Gabapentinoids, found in preliminary studies to reduce ICa,L window current by shifting LTCC voltage-dependent activation to depolarized potentials, will be used as pilot compounds. Based on the success of preliminary studies in single cells and full hearts, the ability of these drugs to prevent or suppress VT/VF will be assessed in whole rabbit and rat hearts under EAD-favoring conditions (oxidative stress, hypokalemia). Establishing the VT/VF-preventing efficacy of late ICa,L reduction in two small animal models will justify translation to larger mammalian models and eventually humans. Aim 2, is designed “to identify the molecular mechanisms underlying late ICa,L reduction by roscovitine and gabapentinoids, prototype members of a potential new class of antiarrhythmic action”. The investigators will take advantage of their recent breakthrough in optically tracking molecular transitions of the human CaV1.2 channel using Voltage Clamp Fluorometry to determine the mechanism by which pilot compounds modify the LTCC to reduce late ICa,L. Specifically, Aim 2A will “identify the molecular mechanisms underlying pedestal ICa,L reduction by roscovitine” and Aim 2B will “identify the molecular mechanisms underlying window ICa,L reduction by gabapentinoids”. This information will reveal how next-generation antiarrhythmics should act on the LTCC. Thus, this proposal has two main novel aspects: it sets the basis for a conceptually new class of antiarrhythmics (LTCC gating modifiers) and directs future rational drug design for the LTCC molecule.