CARDIAC TRANSIENT OUTWARD CURRENT

心脏瞬态外向电流

• 批准号: 6079339
• 负责人: HAROLD CARL STRAUSS
• 金额: $ 16.74万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-06-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6079339
• 关键词: Xenopus oocyte; chimeric proteins; complementary DNA; conformation; ferrets; gene expression; gene mutation; heart cell; molecular cloning; muscle cells; northern blottings; nucleic acid sequence; polymerase chain reaction; potassium channel; protein structure function; site directed mutagenesis; transfection /expression vector; voltage /patch clamp; voltage gated channel

Atrial and ventricular arrhythmias represent a significant cause of morbidity and mortality in patients with different forms of heart disease. Recent studies have raised widespread concern about the adverse effects of current Class I anti-arrhythmic drugs used to treat these arrhythmias. These concerns have spurred interest in Class III agents whose action is mediated through action potential prolongation, usually via blockade of K+ channels. The affinity of such compounds typically shows a complex dependency upon the conformational state of the channel. Our limited understanding of the action of these agents is limited by our understanding of the voltage dependent and voltage insensitive transitions which accompany activation. A quantitative and molecularly based model of the activation process and its coupling to inactivation is a prerequisite for elucidating the nature of the complex blocking action of Class III agents. Therefore, this proposal seeks to characterize a cardiac transient outward K+ current which plays a significant role in determining human action potential duration. Block of transient outward currents appears to be less likely to induce triggered activity than block of delayed rectifier K+ channels. Because of the unique similarities between the human and ferret cardiac I/to and the near identity of our ferret (FK1) and the human (HK1) clone, our objective will be to develop a molecularly based biophysical model of FK1. This study will combine voltage-clamp, single channel, gating current and mutagenesis studies of FK1 in oocytes and CHO cells for model development. We will test the ability of this model to define the mechanism of action of a closed channel blocking compound (4- aminopyridine). This model will incorporate transitions will correspond to both independent movement of single subunits and cooperative interactions between subunits during the activation process. In activation will be modeled as coupled to activation by electrostatic, hydrophobic and allosteric interactions in an effort to characterize both the development of and recovery from inactivation. Ultimately, elucidation of channel structural and functional features may help identify newer and more efficacious channel blockers.

房性和室性心律失常是 不同心脏类型患者的发病率和死亡率 疾病。最近的研究引起了人们对不利因素的广泛关注 当前I类抗心律失常药物治疗这些心律失常的疗效 心律不齐。这些担忧激起了人们对III类特工的兴趣 其作用是通过动作电位延长来调节的，通常 通过阻断K+通道。这类化合物的亲和力通常 显示了对通道构象状态的复杂依赖关系。 我们对这些代理人的行动的有限了解受到我们的 对电压依赖和电压不敏感的理解 伴随着激活而来的转变。一种定量的和分子的 基于模型的激活过程及其与失活的耦合 是阐明复杂阻塞的性质的先决条件 第III类代理人的行动。因此，这项建议旨在 描述心脏瞬间外向K+电流的特征 在确定人类动作潜在持续时间方面的重要作用。块 瞬时外向电流似乎不太可能诱发 触发活动比阻断延迟整流K+通道。因为 人类和雪貂心脏I/TO和 我们的雪貂(FK1)和人类(HK1)克隆的近乎相同的 目标将是开发一种基于分子的生物物理模型 FK1.本研究将电压钳位、单通道、门控相结合 FK1在卵母细胞和CHO细胞模型中的研究现状及诱变作用 发展。我们将测试此模型定义 闭合通道阻滞剂(4- 氨基吡啶)。这一模式将纳入相应的过渡 对于单个亚基的独立运动和协作 激活过程中亚基之间的相互作用。在……里面 激活将被建模为通过静电耦合到激活， 疏水和变构相互作用，以努力表征两者 失活的发展和恢复。最终， 阐明通道的结构和功能特征可能会有所帮助 确定更新、更有效的通道阻滞剂。