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

项目概要： 这些研究的动机是迫切需要一种新的有效和安全的抗肿瘤药物， 防止VT/VF而不损害EC耦合。CaV通道阻滞剂（IV类抗肿瘤药，如 如地尔硫卓（Diltiazem）和维拉帕米（Verapamil））由于其负性肌力作用而具有有限的治疗价值。这些 研究人员最近发现，致瘤性埃兹可以被最小的 L-型Ca通道生物物理参数的改变。至关重要的是，这些演习 共同之处在于它们都降低L型Ca电流的晚期分量（晚期伊卡，L）。选择还原型 晚期伊卡，L的益处是使峰值伊卡，L基本上保持完整，保持收缩性。遗憾的是， 30年前就假设了伊卡，L窗口电流与EAD形成的相关性， 这个想法已经出现了。研究人员最近的研究表明， VT/VF的动物模型现在已经准备好被快速实施：目标1提出“评估 LTCC门控改性剂选择性地减少伊卡，L的晚期组分作为新的 不阻断峰值伊卡，L”的抗血小板药物类别。具体而言，目标1A将“确认 潜在的基座伊卡，L减少使用LTCC门控改性剂”，并确定试点的功效 选择性降低晚期伊卡，L：roscovitine对映体的化合物，已知其降低伊卡，L基座电流。 目标1B将“验证使用LTCC门控降低伊卡，L窗口电流的抗干扰潜力 修饰语”。Gabapentinoids，在初步研究中发现，通过改变LTCC来降低伊卡，L窗口电流 电压依赖性激活去极化电位，将被用作先导化合物。基于成功 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），在整个家兔和大鼠心脏中进行评估。 在两个小动物模型中建立晚期伊卡，L降低的VT/VF预防功效将证明 转化为更大的哺乳动物模型，最终转化为人类。目标2旨在“确定 Roscovitine和gabapentinoids降低晚期伊卡和L的分子机制，原型 一个潜在的新类别的抗疟疾行动的成员”。调查人员将利用他们的 最近在使用电压光学跟踪人CaV1.2通道的分子跃迁方面取得了突破 钳位荧光测定法以确定先导化合物修饰LTCC以减少晚期细胞凋亡的机制。 伊卡湖具体而言，目标2A将“通过以下方式确定基座伊卡，L减少的分子机制： roscovitine”和Aim 2B将“通过以下方式确定窗口伊卡，L降低的分子机制： 加巴喷丁类”。这些信息将揭示下一代抗静电剂应如何作用于LTCC。 因此，这个建议有两个主要的新颖方面：它为一个概念上新的类别奠定了基础， LTCC门控修饰剂（LTCC gating modifiers）的研究，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.