CALCIUM-ACTIVATED POTASSIUM CHANNELS IN SKELETAL MUSCLE

骨骼肌中钙激活的钾通道

• 批准号: 3466917
• 负责人: ANDREW L BLATZ
• 金额: $ 7.23万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-12-01 至 1993-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3466917
• 关键词: calcium; gene expression; histochemistry /cytochemistry; laboratory rat; membrane permeability; muscle cells; neural information processing; neurons; potassium channel; spinal cord; striated muscles; synapses; tissue /cell culture; voltage /patch clamp

The ultimate goal of the research described in this proposal is to fully characterize the properties of small conductance, apamin- blocked Ca-activated K channels (SK channels) that are probably responsible for the sustained afterhyperpolarization (AHP) in tissue cultured rat skeletal muscle. The kinetics, permeability properties and block of SK channels will be examined and the roles of SK channels and other Ca-activated K channels in muscle excitation will be determined. The modulation of SK channels by innervation will be studied, particularly addressing whether or not functional synapse formation is required for channel regulation. Currents through single SK channels will be recorded using the patch voltage clamp technique. Distributions of open and shut channel events will be fitted with sums of exponentials. The number of exponential components required to fit these distributions suggests a minimum number of the kinetic states that underlie SK channel activity. The apparent number of Ca ions that bind during activity will be determined by measuring the slopes of Hill plots of the percent of time the channel is open at several different intracellular Ca concentrations. Interval distributions predicted by several kinetic models will be compared with the experimentally observed distributions in order to find the models that are the most consistent with the experimental data. Permeability properties will be examined by several methods which will address the selectivity of SK channels as well as examine possible ion-channel interactions such as multiple ion occupancy. The block by apamin, a toxin that has a very high affinity for SK channels, will be characterized at the single channel level to investigate the mechanism of block. The roles of SK channels and large conductance Ca-activated channels (BK channels) will be examined by intracellular potential recording while, at the same time, monitoring single channel currents through a cell-attached membrane patch. With this technique it will be possible to observe which channels are active during the various phases of the action potential, particularly during the AHP. Neural modulation of SK channels will be studied by monitoring the muscle cells for SK channels and synapse formation in the presence of growing spinal neurons and/or media conditioned by neurons. These studies will enhance our knowledge about how ion channels function, how the channel properties affect the functioning of excitable cells, and give insights about how neurons can regulate the expression of ion channels.

该提案中描述的研究的最终目标是 充分表征小电导的特性，apamin- 阻塞的CA激活K通道（SK通道）可能是 负责在 组织培养的大鼠骨骼肌。 动力学，渗透性 将检查属性和SK通道的块和角色 肌肉中的SK通道和其他CA激活的K通道 激发将被确定。 通过 将研究神经，特别是解决是否 通道调节需要功能突触形成。 通过单个SK通道的电流将使用 贴片电压夹技术。 开放和关闭的分布 频道事件将装有指数总和。 这 适合这些的指数组件数量 分布表明，最少数量的动力学状态 SK频道活动的基础。 明显的ca离子数量 在活动期间结合将通过测量的斜率来确定 频道开放的时间百分比的山丘图几个 不同的细胞内Ca浓度。 间隔分布 将通过几个动力学模型进行预测 实验观察到的分布以找到模型 与实验数据最一致的是。 渗透率属性将通过几种方法检查 将解决SK频道的选择性并检查 可能的离子通道相互作用，例如多个离子占用率。 Apamin的块，一种对SK具有很高亲和力的毒素 通道将在单个通道级别进行表征 研究块的机理。 SK频道和 大型电导CA激活通道（BK通道）将是 通过细胞内潜在记录检查，而在相同的情况下 时间，通过细胞连接监视单个通道电流 膜片。 通过这种技术，可以观察到 在动作的各个阶段，哪些通道处于活动状态 潜力，特别是在AHP期间。 SK的神经调节 将通过监测SK的肌肉细胞来研究通道 在生长脊柱的情况下，通道和突触形成 神经元和/或由神经元调节的培养基。 这些研究会 增强我们对离子通道的功能的了解，如何 信道特性会影响可激发细胞的功能，并且 关于神经元如何调节离子表达的见解 频道。