MECHANISMS OF IONIC CHANNEL ACTIVITY

这项研究提案的总体目的是确定 两种不同离子的性质及其动力学机制 细胞膜上的通道：钙激活的钾通道和 大电导的电压依赖性氯离子通道。洋流 培养大鼠肌膜单个离子通道的流动 使用贴片在电压钳下记录骨骼肌细胞 钳夹技术。有了这种电生理学技术， 通过观察(通过阶跃变化)研究单通道的动力学 在当前)当单通道打开和关闭时。钠、钾、钙的影响 和镁离子，[Ca]离子的阶跃变化，以及可能的磷酸化 钙激活的钾通道的活性将被表征。这个 钙激活钾通道开放的观察机制 还将检查倾向于以突发方式出现的通道。的影响 膜电位对失活、失活和去除失活的影响 对于电压相关的大电导的c1通道，也将 以及该通道对各种离子的渗透性。 上述数据将用于获取有关打开数量的信息 和关闭状态，打开状态和关闭状态的平均寿命，以及 不同状态之间的转换的速率常数 频道。这些发现将被用来制定一个动力学方案 每个频道。钙激活的钾通道调节重复放电 并影响肌肉的膜电位和兴奋性。C1号 大电导通道也会影响膜的兴奋性。至 了解神经和肌肉膜的特性和功能，它 要了解这两种类型的属性和机制， 频道。了解这些渠道也有助于理解和 治疗神经和肌肉疾病，作为治疗剂和毒素经常 对细胞膜上的离子通道发挥特殊作用。

The overall purpose of this research proposal is to determine the properties and underlying kinetic mechanisms of two different ionic channels in cell membranes: the calcium-activated potassium channel and a voltage dependent chloride channel of large conductance. Currents that flow through single ionic channels in the sarcolemma of cultured rat skeletal muscle cells will be recorded under voltage clamp using the patch clamp technique. With this electrophysiological technique it is possible to study the kinetics of single channels by observing (through step changes in the current) when single channels open and close. The effects of Na, K, and Mg ions, step changes in [Ca] ion, and possible phosphorylation on the activity of the Ca-activated K channel will be characterized. The mechanism underlying the observation that openings of the Ca-activated K channel tend to occur in bursts will also be examined. The effect of membrane potential on activation, inactivation, and removal of inactivation for the voltage dependent C1 channel of large conduictance will also be characteized, as well as the permeability of this channelto various ions. The above data will be used to obtain information about the number of open and closed states, the mean lifetimes of the open and closed states, and the rate constants for transitions between the various states for each channel. These findings will then be used to develop a kinetic scheme for each channel. The Ca-activated K channel modulates repetitive firing in neurons and affects membrane potential and excitability in muscle. The C1 channel of large conductance would also affect membrane excitability. To understand the properties and function of nerve and muscle membranes, it will be necessary to understand the properties and mechanisms of these two channels. Understanding these channels may also help in understanding and treating nerve and muscle disease, as therapeutic agents and toxins often exert their specific effects on ionic channels in cell membranes.