MOLECULAR DETERMINANTS OF POTASSIUM CHANNEL DRUG BLOCK

描述（申请人摘要）：本研究的长期目标是 了解心脏兴奋性的分子基础。 本提案中 研究人员将研究电压门控K+的分子决定因素， 抗心律失常药物和局部麻醉药阻断通道。 电压依赖 K+通道在控制心脏兴奋性方面起关键作用， 复极化并且是许多新型抗心律失常药物的分子靶点 剂. 研究人员将利用克隆的亚基， 促进天然心脏电流（Kv1.5、Kv4.2、HERG、KvLQT 1）。 越来越多的证据表明，通道的分子结构 蛋白质复合物包括改变功能的辅助亚基（β 亚基，minK），其可能影响药物结合。 假设是 包括S6片段中的特定孔残基参与 开放通道阻断药物的结合。 此外，调查人员将 测试疏水相互作用是否决定亲和力， 药物封闭立体选择性。 此外，他们还将测试氨基是否 孔衬段中的酸差异解释了异构体特异性 对抗肿瘤药物的亲和力。 他们将讨论是否 抗肿瘤药物利用保守的受体位点 β-亚基通过测试的相互作用，在内口的 毛孔 最后，他们将测试KcLQT 1的内在药理学是否 当它与minK亚基共组装以重建 本地电流Iks。在这些研究中，他们将使用现代技术 分子生物学的方法来修饰通道结构和各种补丁 钳位技术，以测试特定的功能变化。 结果将 可以用数学和热力学模型来解释， 门控和药物作用。 这些研究将解决分子决定因素 药物阻断和药物与激活和失活门的相互作用。 从这个项目中获得的信息将扩大我们对 这些重要通道的分子药理学， 导致对心律失常机制的更好理解， 开发更好的抗疟疾治疗方法。

DESCRIPTION (Applicant's Abstract): The long term goal of this research is to understand the molecular basis of cardiac excitability. In this proposal the investigators will study molecular determinants of voltage-gated K+ channel block by antiarrhythmic drugs and local anesthetics. Voltage-gated K+ channels play a crucial role in controlling cardiac excitability and repolarization and are the molecular target for many new antiarrhythmic agents. The investigators will utilize cloned subunits that are considered to contribute to native cardiac currents (Kv1.5, Kv4.2, HERG, KvLQT1). Increasing evidence indicates that the molecular architecture of the channel protein complex includes function-altering accessory subunits (beta subunits, minK) which may impact on drug binding. The hypotheses to be tested include that specific pore residues in the S6 segment are involved in binding of open channel blocking drugs. Furthermore, the investigators will test whether hydrophobic interactions determine affinity and stereoselectivity of drug block. In addition, they will test whether amino acid differences in the pore lining segments explain isoform-specific affinities for antiarrhythmic drugs. They will address whether antiarrhythmic drugs utilize a conserved receptor site for inactivating beta-subunits by testing for mutual interactions in the inner mouth of the pore. Finally, they will test whether the intrinsic pharmacology of KcLQT1 is altered when it co-assembles with the minK subunit to reconstitute the native current Iks. In these studies they will use contemporary techniques of molecular biology to modify channel structure and a variety of patch clamp techniques to test for specific functional changes. The results will be interpreted in terms of mathematical and thermodynamic models for channel gating and drug action. These studies will address molecular determinants of drug block and drug interactions with activation and inactivation gates . The information gained from this project will expand our knowledge of the molecular pharmacology of these important channels, which may ultimately result in improved understanding of mechanisms of arrhythmias and the development of better antiarrhythmic treatments.