DRUG CHANNEL INTERACTIONS ALTERED BY ABNORMAL CONDITIONS

延长心脏动作电位，从而产生有效的难治性 通过抑制K通道的周期可能提供重要的抗心律失常 (三)在设置折返性心律失常方面的行动。目前 现有的III类药物对不到30%或40%的人有效 患者，并在某些情况下变得心律失常。去设计 更好的III类药物，关于分子机制的信息 毒品行动是必要的。传统的方法采用心脏手术。 研究药物对天然钾通道的影响。虽然 关于药物的阻断效力，我们可以学到很多东西，这些方法是 受限于单通道分析的困难，以及无法 专门修改渠道结构并检查所产生的 毒品行为的变化。在本申请中，我们提出了一种新方法： 从心脏文库研究药物对K通道克隆的作用。三 将研究频道的类型：瞬变向外(Kv1.4)、快速 延迟整流(Kvl.2)和慢速延迟整流(ISK)。我们会 对药物-通道相互作用进行详细的动力学分析 全单元和单通道电平。更重要的是，通过信息 关于这些可用渠道的结构-功能关系和 特定突变它们的序列的能力，我们现在可以解决 药物作用的分子机制问题。我们将重点关注3个方面 药物：奎尼丁和氯氟溴铵阻断所有三个通道，但 他们行动中的质的和量的差异；质地障碍 具体来说就是ISK。我们已经提出了关于以下机制的假设 并将在拟议的实验中对其进行测试。另一个 关于抗心律失常或促心律失常活动的重要问题 药物的作用是它们的作用如何被疾病条件改变 作为缺血和脑梗塞。由于抗心律失常药物的作用 取决于它们的底物和心律失常的发生机制， 对于研究药物在异常情况下的作用很重要。在这 应用我们将研究离子组成和微扰如何 脑缺血和梗塞时可能发生的PKA和PKC的激活 可以调节Kv1.4、Kv1.2和ISK的功能及其反应 K通道阻滞剂。我们结合电生理学的方法 分子生物学技术将产生更准确的信息 了解药物作用的机制以及疾病对药物作用的影响 条件，因此可能有助于新药的设计或更好地使用 目前可用的药物。

Prolonging cardiac action potential and thus the effective refractory period by inhibiting K channels may provide an important antiarrhythmic (class III) action in the setting of reentrant arrhythmias. Currently available class III drugs are effective in less than 30 or 40% of the patients, and become proarrhythmic under certain conditions. To design better class III drugs, information about the molecular mechanisms of drug actions is needed. The conventional approaches employ cardiac tissues or myocyte to study drug effects on native K channels. Although much about drugs' blocking potencies can be learned, these approaches are limited by the difficulties of single channel analysis, and the inability to specifically modify channel structure and examine the resultant changes in drug actions. In this application, we propose a new approach: studying drugs actions on K channel clones from cardiac libraries. Three types of channels will be studied: transient outward (Kvl.4), rapid delayed rectifier (Kvl.2) and slow delayed rectifier (IsK). We will perform detailed kinetic analysis of drug-channel interactions at both whole-cell and single-channel levels. More importantly, with information about the structure-function relationship of these channels available and the ability to specifically mutate their sequences, we can now address the issue of molecular mechanisms of drug actions. We will focus on 3 drugs: quinidine and clofilium block all three channels but with qualitative and quantitative differences in their actions; proquil blocks IsK specifically. We have formulated hypotheses about the mechanisms of drug actions and will test them in the proposed experiments. Another important question regarding anti arrhythmic or proarrhythmic activities of drugs is how their actions may be modified by diseased conditions such as ischemia and infarction. Since the actions of antiarrhythmic drugs depend on their substrates and the mechanisms of arrhythmogenesis, it is important to study drug actions under abnormal conditions. In this application we will study how perturbations in ionic composition and activation of PKA and PKC likely to occur during ischemia and infarction can modulate the function of Kv1.4, Kv1.2 and IsK, and their responses to K channel blockers. Our approach of combining electrophysiological and molecular biological techniques will generate more exact information abut the mechanism of drug actions and how they are modified by diseased conditions, and thus may aid the design of new drugs or better usage of currently available drugs.