CELLULAR CONTROL OF MEMBRANE CURRENTS

本项目的长期目标是确定 细胞控制其膜的离子电流。 两种观点 正在使用：第一种方法侧重于膜的变化， 可以由环境变化引起的属性 膜的 这些研究使用蜗牛的神经元细胞体（Limnea， Hessel，Helisoma），对它进行了复杂的电生理学研究。 可能 一种内灌注电压钳技术已经被用于 开发的，它允许细胞间的影响，以及 细胞外的离子和分子对膜电流的影响。 将研究钙电流对细胞内 分子通常被灌注耗尽， 通过外部施加神经递质产生电压依赖性电流， 膜特性与细胞功能的关系， 膜电流的体外维持，和生长的影响， 温度对膜性能的影响。 第二种方法检查 细胞膜特性的变化，可以通过点突变产生， 基因组 这些研究将在线虫的肌肉细胞上进行 秀丽隐杆线虫，或果蝇的神经元细胞体 果蝇;这两种动物都便于遗传学研究。 的 内部灌注电压钳技术已被证明适用于细胞 像这些一样小。 野生型动物的膜电流将是 确定，然后将来自许多行为突变体的细胞 检查膜性能的变化。 由于重视 细胞间Ca++在控制肌肉收缩，递质释放， 和其他细胞功能，主要注意力将在所有的 上述研究对Ca电流和重叠K电流的影响， 其决定Ca++流入细胞。 发现的机制或 该项目将大大有助于 了解涉及改变状态的神经和肌肉疾病 膜兴奋性或突触功效的影响。

The long-term goal of this project is to determine the mechanisms by which cells control the ionic currents of their membranes. Two approaches are being used: the first approach focuses on the changes in membrane properties that can be induced by changes in the environment of the membrane. These studies use the neuronal cell bodies of snails (Limnea, Helix, Helisoma), on which sophisticated electrophysiological studies are possible. An internal-perfusion, voltage-clamp technique has been developed which allows the effects of interacellular, as well as extracellular, ions and molecules on membrane currents to be measured. Studies will be made of the dependence of Ca currents on intracellular molecules normally depleted by perfusion, the modulation of voltage-dependent currents by external application of neurotransmitters, the relation between membrane properties and cell function, the alteration of membrane currents by maintenance in vitro, and the effects of growth temperature on membrane properties. The second approach examines the changes in membrane properties that can be produced by point mutations in the genome. These studies will be done on the muscle cells of the nematode Caenorhabditis elegans, or neuronal cell bodies of the fruit fly Drosophila; both animals are convenient for genetic studies. The internal-perfusion, voltage-clamp technique has proven applicable to cells as small as these. The membrane currents of the wild-type animals will be determined, and then cells from a number of behavioral mutants will be examined for alterations in membrane properties. Due to the importance of interacellular Ca++ in controlling muscle contraction, transmitter release, and other cellular functions, primary attention will be given in all of the above studies to effects on the Ca current and overlapping K currents, which determine the influx of Ca++ into the cell. Mechanisms discovered or elucidated by this project will contribute significantly to the understanding of neural and muscular diseases that involve altered states of membrane excitability or synaptic efficacy.