K+ CHANNELS--STRUCTURE/FUNCTION RELATION & PHARMACOLOGY

我们研究的长期目标是了解心脏离子 通道由药理学试剂和病理学试剂调节， 条件 这些信息对于设计有效的 抗心律失常药物和心律失常的有效管理 在病理条件下。实现这一目标的关键是 深入了解结构与功能的关系 心脏离子通道。 分子克隆技术的进展 诱变技术使我们能够将克隆的通道 亚单位与天然通道在心脏，并操纵他们的 以特定的方式，使通道之间的关系 结构和功能可以推断。 本申请的重点 是快速（IKr）和慢速（IKs）延迟整流钾通道， 心 IKr和IKs是动作电位的主要决定因素 持续时间（APD）。 他们在维护 正常的心脏电活动与其独特的门控有关 特性. IKr的快速失活和再激活过程 在其I-V引起向内整流。这有助于保持 在阶段2期间的正平台阶段和足够的外向电流 第三阶段复极化 另一方面，缓慢的激活和 IKs的失活过程是APD的重要机制 通过心率的变化进行调节。 这些缓慢的门控过程 与IKs的两个亚基KvLQT 1和 他是。 IKr和IKs也是K通道调节剂的重要靶标。 关于目前的作用机制和作用地点的信息 可用的IKr和IKs上的K通道调节剂可以帮助设计新的 抗抑郁药 我们建议使用克隆的K通道亚基作为 模型（IKr的hERG和IKs的KvLQT 1/hIsK），并结合联合收割机位点- 定向诱变和电生理技术来研究 结构功能关系和药物通道相互作用。 四 具体目的是：（1）研究 hERG独特的门控行为。（2）探讨阿齐利特的作用机制 （3）研究其对hERG的激动和拮抗作用。 KvLQT 1参与了与hIsK的相互作用。（4）研究KvLQT 1与hIsK的相互作用机制 阿齐利特和奎尼丁对IKs的差异作用。 是 预计这些研究的结果将改善我们的 了解IKr和IKs的功能和调节， 阿齐利特和奎尼丁的研究应该提供深远的 药物对K通道的作用。

The long-term objective of our research is to understand how cardiac ion channels are modulated by pharmacological agents and by pathological conditions. This information is critical for the design of efficacious antiarrhythmic agents and effective management of cardiac arrhythmias under pathological conditions. The key to achieving this objective is to have a thorough understanding of the structure-function relationship of cardiac ion channels. The advance of molecular cloning and mutagenesis techniques has allowed us to correlate cloned channel subunits with native channels in the heart, and to manipulate their primary sequences in specific ways so that the relation between channel structure and function can be deduced. The focus of this application is the rapid (IKr) and slow (IKs) delayed rectifier K channels in the heart. IKr and IKs are the primary determinants of action potential duration (APD) in cardiac myocytes. Their importance in maintaining the normal cardiac electrical activity is related to their unique gating properties. The fast inactivation and reactivation processes of IKr cause an inward rectification in its I-V. This helps maintain a positive plateau phase during phase 2 and yet sufficient outward current for phase 3 repolarization. On the other hand, the slow activation and deactivation processes of IKs are an important mechanism for APD regulation by changes in the heart rate. These slow gating processes are related to the interactions between two subunits of IKs: KvLQT1 and hIsK. IKr and IKs are also important targets for K channel modulators. Information about the mechanisms and sites of actions of currently available K channel modulators on IKr and IKs may aid the design of new antiarrhythmic drugs. We propose to use cloned K channel subunits as a model (hERG for IKr and KvLQT1/hIsK for IKs), and combine site- directed mutagenesis and electrophysiological techniques to study the structure-function relationship and drug-channel interactions. Four Specific Aims are proposed: (1) To study the structural basis for the unique gating behavior of hERG, (2) To study the mechanisms of azimilide s agonist and antagonist actions on hERG, (3) To study the domains of KvLQT1 involved in interactions with hIsK, (4) To study the mechanisms of differential actions of azimilide and quinidine on IKs. It is anticipated that results from these studies will improve our understanding of the function and modulation of IKr and IKs, and the studies on azimilide and quinidine should provide far-reaching implications for drug actions on K channels.