Ion channels in regulation of excitable membranes

描述(由申请人提供)：可兴奋性膜活性的变化是脊椎动物神经系统内功能改变的基石。神经系统活动的改变反过来又是脊椎动物行为变化的基石。因此，了解兴奋性膜的调节有助于我们理解神经系统的功能，并将这些变化与体内行为变化联系起来，为全面理解行为变化及其生物学基础提供了有力的途径。这种研究的理想模型是弱电鱼类B.pinniaudatus，它能产生电场，即所谓的电子器官放电(EOD)，用于电子定位和通信。EOD波形的幅度和持续时间随明显受类固醇效应控制的环境变量而变化。由于EOD是由电子器官内所有细胞的同步离子膜电流引起的，EOD波形的变化反映了单个细胞离子电流的变化。通过确定EOD波形变化的细胞和分子机制，有可能确定将环境控制的行为与其神经、内分泌和细胞原因联系起来的连续因果关系链。本课题将应用单单位记录、双电极电压钳和膜片钳记录等电生理技术，研究羽尾双歧杆菌调控EOD变化的生理机制。该项目的具体目标是：1)将EOD的相位与其相应的细胞外电位和细胞内动作电位联系起来；2)确定哪些离子电流对细胞外电位和细胞内动作电位的两个阶段有贡献；3)确定EOD波形的快速变化在单个细胞的细胞外电位、细胞内电位和细胞内电位中表达的机制；以及4)确定当EOD的幅度和持续时间发生变化时，特定离子电流如何变化。

DESCRIPTION (provided by applicant): Change in the activity of excitable membranes is a cornerstone of functional modification within the vertebrate nervous system. Modification of nervous system activity, in turn, is a cornerstone of behavioral change in vertebrates. Thus, understanding the regulation of excitable membranes contributes to our understanding of nervous system function and relating these changes to in vivo behavioral changes presents a powerful approach to an integrated understanding of behavior change and its biological bases. An ideal model for such research is the weakly electric fish, B. pinnicaudatus, which generates electric fields, known as electric organ discharges (EODs), for electrolocation and communication. The amplitude and duration of the EOD waveform varies in response to environmental variables apparently controlled by steroid effects. Because the EOD results from synchronized ionic membrane currents of all electrocytes within the electric organ, changes in EOD waveform reflect changes in ion currents of individual electrocytes. By determining the cellular and molecular mechanisms of EOD waveform change it is possible to determine a chain of continuous causal connections relating environmentally controlled behavior to its neural, endocrine, and cellular causes. The project proposed here will apply electrophysiological techniques including single unit recording, two-electrode voltage clamp, and patch-clamp recording to discover the physiological mechanisms by which B. pinnicaudatus regulate these changes inEOD. The project's specific aims are to 1) relate the phases of the EOD to its corresponding extracellular potentials and intracellular action potentials 2) determine which ion currents contribute to the two phases of the extracellular potential and to the intracellular action potential 3) determine the mechanisms by which rapid changes in EOD waveform are expressed in the extracellular potentials and intracellular potentials and intracellular potentials of individual electrocytes, and 4) determine how specific ion currents change when the EOD changes in amplitude and duration.