MECHANISMS OF IONIC CHANNEL ACTIVITY

本研究提案的总体目的是确定 两种不同离子的性质和潜在的动力学机制 细胞膜上的通道：钙激活钾通道和 大电导的电压依赖性氯离子通道。 的电流 培养大鼠心肌细胞膜单离子通道的流量 将在电压钳下使用贴片记录骨骼肌细胞 钳位技术 有了这种电生理技术， 通过观察（通过阶跃变化）来研究单通道的动力学 在电流中）当单个通道打开和关闭时。 Na，K， 和Mg离子，[Ca]离子的阶跃变化，以及可能的磷酸化作用。 将表征Ca激活的K通道的活性。 的 观察到钙激活钾通道的开口 也将检查信道倾向于在突发中发生。 的影响 活化、失活和去除失活的膜电位 对于大磁阻的电压相关C1通道， 表征，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开放数量的信息 和闭合状态，打开和闭合状态的平均寿命，以及 对于每一个，各种状态之间的转变的速率常数 频道 这些研究结果将用于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， 神经元和影响膜电位和兴奋性的肌肉。 所述C1 大电导通道也会影响膜的兴奋性。 到 了解神经和肌肉膜的特性和功能， 将有必要了解这两个属性和机制 渠道 了解这些渠道也可能有助于理解和 治疗神经和肌肉疾病，作为治疗剂和毒素， 对细胞膜中的离子通道发挥其特定作用。

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.