SODIUM CHANNEL GATING IN MODELS OF MYOTONIA

本方案的目的是：1)研究钠离子通道 大鼠骨骼肌失活，2)研究大鼠 人肌肉强直性疾病模型的建立 兴奋性可能受损。关于钠通道的两个假说 将对门控进行测试。首先，钠电流增加 通过在大鼠骨骼肌中产生肌强直的治疗。 第二，钠电流密度的增加是由于 电压依赖性钠通道失活的改变。这个 采用的技术是：1)松片电压钳位将 用于测量钠电流，以及2)单纤维类型 纤维将通过组织化学染色和钠 十二烷基硫酸酯聚丙烯酰胺凝胶电泳法(SDS-PAGE)。 这些实验测量了对照组和强直性肌强直患者的钠电流。 使用本实验室开发的肌肉技术，允许 几个小时内稳定的细胞电流记录。肌强直 老鼠的肌肉将通过以下方式产生：1)将纤维浸泡在氯化物中- 稀溶液，2)芳香族羧酸处理纤维 酸以降低氯离子电导，以及3)给大鼠20， 25-二氮卓醇酯。钠通道FAST的电压依赖性 并将对缓慢的失活进行研究，以检查变化是否 钠电流密度的变化可以归因于FAST 或缓慢失活。 这些项目将提供1)有关兴奋性的新信息 和2)可能有新的关于 不同形式的肌强直的病理生理学。

The objectives of this proposal are: 1) to study sodium channel inactivation in rat skeletal muscle, and 2) to investigate rat model of human muscle myotonic disorders in which membrane excitability may be impaired. Two hypotheses about sodium channel gating will be tested. First, that sodium currents are increased by treatments which produce myotonia in rat skeletal muscle. Second, that the increase in sodium current density is due to an alteration in voltage-dependent sodium channel inactivation. The techniques employed are: 1) the loose-patch voltage clamp will be used to measure sodium currents, and 2) the fiber type of single fibers will be determined by histochemical staining and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The experiments measure sodium currents in control and myotonic muscle using techniques developed in this laboratory that permit stable current recordings of cells for several hours. Myotonia in rat muscle will be produced by: 1) bathing a fiber in a chloride- deficient solution, 2) treating fibers with aromatic carboxylic acids to reduce chloride conductance, and 3) treating rats with 20, 25-diazacholesterol. The voltage dependence of sodium channel fast and slow inactivation will be studied to examine whether changes in sodium current density can be attributed to alterations in fast or slow inactivation. These projects will provide 1) new information on the excitability of mammalian skeletal muscle; and 2) possibly new information on the pathophysiology of different forms of myotonia.