MECHANISMS OF M-CHANNEL MODULATION

M 通道调制机制

• 批准号: 3478370
• 负责人: NEIL V MARRION
• 金额: $ 8.82万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-04-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3478370
• 关键词: Rana; acetylcholine; action potentials; electrophysiology; enzyme induction /repression; membrane channels; neural conduction; neural initiation; neurophysiology; protein kinase C; second messengers; single cell analysis; voltage /patch clamp

Neurotransmitter modulation of a membrane current(s) and the implications on nerve excitability has been extensively studied. This project is concerned with the modulation of the M-current, which plays a major role in the sub-threshold range for action potential initiation, causing membrane hyperpolarization and therefore, reducing cell excitability. Neurotransmitters, eg: acetylcholine and LHRH, can suppress the M-current. This produces membrane depolarization and increased input resistance, making the cell more excitable and likely to fire action potentials. Enhancing the M-current hyperpolarizes the cell and increases the stabilizing effect on membrane excitability. It is clear therefore, that modulation of the M-current by these factors places it in a unique position to control cell excitability. It is known that the M-current can be inhibited by activators of protein kinase C and enhanced by small increases of intracellular calcium. This application will use electrophysiological techniques to resolve the mechanisms involved in the modulation of the M-current. This includes how the properties of the single channels change upon current modulation and elucidation of which "messengers" may be involved in these effects. To achieve this the application's specific aims consist of two techniques. First, the technique of non-stationary ensemble variance analysis will be used to characterize the M-current, in terms of the single channel number, conductance and opening probability. Using this technique, resolution of how the M-current is suppressed by acetylcholine or LHRH will be possible, determining which channel property is changed by these agents and whether they act by the same mechanism. Once achieved, comparison with known "messengers" will be undertaken. Once this work is completed, resolution of single channel currents will be attempted using the patch-clamp technique. Patch recordings will be carried out in two configurations, "cell-attached" and excised "inside- out" modes. "Cell-attached" experiments will allow study of the modulation of M-channel activity by the agonists. If this is observed, then a soluble second messenger is implicated in this effect. If no effect is observed, excision of channel activity into the "inside-out" configuration will allow direct application o second messengers to the internal surface of the plasma membrane. If successful, a greater understanding of the role of modulation of the M-current in controlling cell activity will be attained. This information will also resolve the source of signals which can regulate the amplitude of the M-current.

膜电流的神经递质调制和 对神经兴奋性的影响已经进行了广泛的研究。这 项目与M-Current的调制有关，该调节播放A 在阈值范围内的主要角色，以进行动作潜在的启动， 引起膜超极化，因此减少了细胞 兴奋性。神经递质，例如：乙酰胆碱和LHRH，可以 抑制M电流。这会产生膜去极化和 增加输入电阻，使细胞更加激发，并可能 消防电势。增强M电流超极化细胞 并增加对膜兴奋性的稳定作用。这是 因此，很明显，这些因素对M电流进行调节 将其置于控制细胞兴奋性的独特位置。 众所周知，蛋白质激活剂可以抑制M电流 激酶C并通过细胞内钙的少量增加而增强。这 应用将使用电生理技术来解决 M-电流调制涉及的机制。这包括 当电流调制时，单个通道的属性如何变化 并阐明了这些效果可能涉及的“使者”。 为了实现这一目标，应用程序的具体目标包括两个 技术。 首先，非平稳合奏方差分析的技术将 用单个通道来用来表征M电流 数量，电导和开放概率。使用此技术， 乙酰胆碱或LHRH抑制M电流的分辨率 将有可能，确定这些渠道属性已通过这些更改 代理商以及它们是否通过相同的机制起作用。一旦实现， 将与已知的“使者”进行比较。 一旦完成工作，单个通道电流的分辨率将 尝试使用贴片钳技术。补丁记录将是 以两种配置进行，“与细胞连接”并在内部切除。 OUT“模式”。细胞连接”实验将允许研究 激动剂对M通道活性的调节。如果观察到 然后，与此效应有关可溶的第二使者。如果没有 观察到效果，将通道活性切除到“内而外” 配置将允许直接应用程序o第二使者到 质膜的内表面。 如果成功的话，对调制的作用有更深入的了解 将获得控制细胞活性的M电流。这 信息还将解决可以调节的信号来源 M电流的振幅。