COMPARATIVE ASPECTS OF IONIC CONDUCTANCES IN NERVE AND HEART CELL MEMBRANES

本项目涉及离子的比较分析。 神经和心脏细胞膜上的电流通道和 这些通道与电活动的关系，具有 特别强调两者中的钾离子通道 不同离子阻滞剂的制备及对这些细胞的影响 频道。在过去的一年里，初步的实验 已经使用的制剂是鱿鱼、巨型轴突和雏鸡 胚胎心脏细胞。这项工作最近集中在 鸡心肌细胞延迟整流钾通道。一个 主要发现是对该组件的测量 采用吸移管电压钳制技术的单电池 在各个方面都可与我们在 使用双微电极电压钳的细胞聚集体 技术。这一结果挑战了主流观点，即 钾离子蓄积在细胞外间隙中的作用 心脏组织。具体地说，这些空间的加载 钾离子被认为在心脏生成中起作用 节律失常。我们的结果表明，这种机制可能不会 要像人们普遍认为的那样重要。

This project is concerned with a comparative analysis of ionic current channels in nerve and heart cell membranes and the relationship of these channels to electrical activity, with a particular emphasis on potassium ion channels in both preparations and the effects of various ionic blockers on these channels. During the past year the primary experimental preparations which have been used are squid giant axons and chick embryonic heart cells. This work has focused recently on the Delayed Rectifier Potassium Channel, IK, in chick heart cells. A major finding has been that measurements of this component in single cells using the suction pipette voltage clamp technique are comparable in every way to our earlier measurements of IK in aggregates of cells using the two-microelectrode voltage clamp technique. This result challenges a prevailing view concerning the role of potassium ion accumulation in the extracellular spaces of cardiac tissue. Specifically, the loading of these spaces by potassium ions is believed to play a role in generating Cardiac Dysrhythmias. Our results suggest that this mechanism may not be as significant as is commonly believed.