VOLTAGE GATED CARDIAC POTASSIUM CHANNELS

本研究的长期目标是研究离子通道的功能 以及它与兴奋性的关系，特别是在心肌细胞中。 在这 在工作中，我使用了一系列的技术和准备工作。 现时的建议 旨在研究心脏钾通道在一个新开发的 表达克隆通道的系统。 表达系统将 特别有价值，因为研究心脏K通道在自然 电池提出了一系列技术难题。 首先， 十多个不同生理学的钾通道 详细分析任何单个钾通道。 第二，有些是 在不到1/100的贴片中观察到，妨碍了可靠的单通道 分析. 分子生物学的最新进展现在提供了前所未有的 克隆和表达个人渠道的机会。 在范德比尔特， 从大鼠和人类心脏中克隆了七种钾通道。 这些蛋白质在非洲爪蟾卵母细胞中表达， 在哺乳动物细胞中表达的通道可能不同。 最近， 已经在哺乳动物细胞系小鼠中实现了稳定表达 L细胞 该研究项目的目的是研究生理 心脏钾通道的药理学特性 在这个新的系统中，并将结果与渠道 在原生细胞中发挥作用。 该表达系统的优点将 被用来详细研究电压和状态依赖 药物与这些通道的相互作用。 电压箝位技术， 包括全细胞，单通道和宏补丁，将用于 分析离子转移、离子选择性、门控特性和药物 这些渠道的敏感性。 数学模型将用于 为进一步分析实验数据提供框架，并 指导更多的实验。 表达通道的属性赢得了 与本地渠道进行比较，进一步了解 对心肌细胞中的总钾电流有贡献的成分。 钾离子通道在心脏调控中起重要作用 兴奋性和复极，是许多可用的目标 和研究性（“III类”）抗肿瘤药。 的信息 从这个项目中获得的知识将扩大我们对 这些重要的渠道，这可能最终导致改善 了解心律失常的机制， 更好的抗抑郁药

The long-term objective of my research is to study ion channel function and its relation to excitability, particularly in cardiac cells. In this work, I use a range of techniques and preparations. The current proposal is aimed at studying cardiac potassium channels in a newly developed system in which cloned channels are expressed. An expression system will be especially valuable because the study of cardiac K channels in native cells presents a series of technical difficulties. First the presence of more than ten potassium channels with diverse physiologies complicates detailed analysis of any individual potassium channel. Second, some are observed in less than 1/100 patches preventing reliable single channel analysis. Recent advances in molecular biology now provide unprecedented opportunities to clone and express individual channels. At Vanderbilt, seven potassium channels have been cloned from rat and human heart. These have been expressed in Xenopus oocytes but processing of such expressed channels may be different in mammalian cells. More recently, stable expression has been achieved in a mammalian cell line, mouse L-cells. The aims of this research project are to study physiological and pharmacological properties of cardiac potassium channels expressed individually in this new system, and to relate to results to channel function in native cells. The advantages of this expression system will be exploited to study in detail the voltage- and state-dependent interaction of drugs with these channels. Voltage clamp techniques, including whole cells, single channel and macropatch, will be used to analyze ion transfer, ion selectivity, gating properties, and drug sensitivity of these channels. Mathematical modelling will be used to provide a framework for further analyzing the experimental data, and to guide additional experiments. The properties of expressed channels win be compared to those of native channels further develop an understanding of the components which contribute to overall K current in cardiac cells. Potassium channels play an important role in controlling cardiac excitability and repolarization, and are the target for many available and investigational ('class III') antiarrhythmic agents. The information gained from this project will expand our knowledge of the function of these important channels, which may ultimately result in improved understanding of the mechanisms of arrhythmias and in the development of better antiarrhythmic drugs.