Cardiac Channels: Targets of Drugs that Affect Kinetics

描述(申请人提供)：心脏病仍然是这个国家的主要死亡原因。影响血压的药物是重要的治疗剂，钙通道阻滞剂已在许多大型临床试验中得到验证，不仅在降低血压方面有效，而且在降低冠心病和中风风险方面也有效。虽然人们普遍认为它们优先阻断血管系统中的L型钙通道，但也有报道称它们也阻断T型钙通道。我们建议研究三种钙通道阻滞剂的结合决定因素和抑制的分子基础：米贝法地尔是以T型钙通道为主要靶点的原型药物，维拉帕米是第一代钙通道阻滞剂(苯烷胺)，它仍然有效地治疗高血压，也是治疗阵发性房性心动过速的一线药物，以及氨氯地平，一种高处方的第四代二氢吡啶(DHP)。我们的实验重点将放在T型钙通道作为这些药物的重要主要或次要靶点上，尽管我们也建议与L通道实验室合作进行药物与T通道和L通道的比较分析，并将电压依赖性钠通道作为米贝拉地尔的次要靶点进行研究。我们的长期目标是了解靶向心脏离子通道的药物分子底物的控制，即它们状态依赖亲和力的结构基础。我们之所以选择这三种药物，是因为它们是与临床应用相关或具有吸引力的治疗药物，以不同的方式与T通道相互作用，并为我们提供机会发现运动功能的重要结构决定因素。我们的策略结合了诱变、全细胞、单通道和门控电流电生理学以及分子建模。

DESCRIPTION (provided by applicant): Cardiac disease continues to be the leading cause of death in this country. Drugs that affect blood pressure are important therapeutic agents, and calcium channel blockers have been validated in a number of large clinical trials as effective in not only lowering blood pressure but also in reducing the risks of coronary heart disease and stroke. Although they are generally thought to preferentially block L-type calcium channels in the vascular system, some of them have also been reported to block T-type calcium channels as well. We propose to investigate the binding determinants and molecular basis of inhibition of three calcium channel blockers: mibefradil, as a prototype drug for which the T-type calcium channel is the primary target, verapamil, a first generation calcium channel blocker (phenylalkylamine), which continues to be effective for treatment of hypertension and also is a first line therapy for paroxysmal atrial tachycardia, and amlodipine, a highly prescribed fourth generation dihydropyridine (DHP). Our experimental focus will be on the T-type calcium channel as an important primary or secondary target of these drugs, although we also propose to collaborate with an L-channel laboratory for comparative analysis between drugs and T- and L-channels and to study voltage dependent Na channels as a secondary target of mibefradil. Our long term goal is to understand the control of the molecular substrate of drugs that target cardiac ion channels, i.e. the structural bases of their state dependent affinities. We have chosen these three agents because they are classes of therapeutic agents that are relevant to or attractive for clinical use, interact with T-channels in distinct ways, and provide us with the opportunity to discover important structural determinants of kinetic function. Our strategy combines mutagenesis, whole cell, single channel, and gating current electrophysiology, and molecular modeling.