NA+ CHANNELS IN NORMAL & ABNORMAL NERVE MEMBRANE

所提出的研究的中心主题是表征细胞 和离子通道表达进化的分子基础， 神经系统 这是在NB 2a的独特模型系统中实现的 神经母细胞瘤细胞，它保留了两个不同的途径， 正常发育的分化方案。 这些细胞在被诱导后 用db cAMP或视黄酸分化，延伸轴突或 树突状突起。 该研究计划侧重于一个 神经元分化的表型特征， Na+通道的亚型，我们以前已经证明， 在“轴突”和“树突”NB 2a细胞之间。 应用范围很广 长期目标是：1）确定细胞和分子 控制神经细胞中Na+通道亚型表达的机制; 20为了确定Na+通道亚型与特异性功能 属性作为不同基因的产物出现;并确定 它们分子结构的差异， 专门的属性，以及它们所服务的角色; 3）应用这些 研究，以进一步了解神经兴奋机制， 正常和疾病状态。 具体的目的和实验设计是：1）表征 蛋白质合成的不同时间进程 两种Na+通道亚型在分化过程中的表达 轴突和树突状NB 2a细胞。 这将包括比较 Na+通道亚型的寿命和周转率; 2） 表征参与表达的mRNA种类的转录物， 在分化的NB 2a细胞中的两种Na+通道亚型，以确定 两种Na+通道亚型是否是不同基因的产物， 种，并确定mRNA转录在Na+通道中的作用 3）建立了一个研究互惠的模型系统 两种Na+通道亚型表达的变化， 神经支配和去神经支配。 主要实验方法 包括：1）表征Na+通道亚型在 通过测量高和低亲和力[3 H]-的NB 2a细胞分化 STX受体; 2）通过以下方法表征Na+通道mRNA种类： 与大鼠脑Na+通道II cRNA探针杂交。 该项目的健康相关性在于， 各种Na+通道亚型在正常和异常 可兴奋膜决定了正常的生理和病理生理 这些组织中的脉冲传导。 NB 2a细胞提供了一个模型， 系统开始研究Na+通道功能和分布 可兴奋膜中的同种型。 这些特性与以下方面有关：1） 神经系统的正常功能; 2）神经系统疾病，如 多发性硬化症、阿尔茨海默病和肌营养不良症;以及3） 心血管冲动传导，心律失常的产生，以及 抗肿瘤剂。

The central theme of the proposed studies is to characterize the cellular and molecular bases underlying the evolution of ion channel expression in the nervous system. This is pursued in a unique model system of NB2a neuroblastoma cell, which have retained two distinct pathways of the differentiation program of normal development. These cells, when induced to differentiate with db cAMP or retinoic acid, extend either axonal or dendritic processes respectively. This Research Plan focuses upon one phenotypic characteristic of neuronal differentiation, the expression of isoforms of the Na+ channel, which we have previously shown to differ between "axonal" and "dendritic" NB2a cells. The application's broad long-term objectives are: 1) To determine the cellular and molecular mechanisms controlling expression of Na+ channel isoforms in nerve cells; 20 To determine whither Na+ channel isoforms with specialized functional properties arise as products of distinct genes; and to determine the differences in their molecular structure which account for these specialized properties, and the roles they serve; 3) To apply these studies to further our understanding of nerve excitability mechanisms in normal and disease states. The specific aims and experimental design are: 1) To characterize the events of protein synthesis which account for the different time courses of expression of the two Na+ channel subtypes during differentiation of axonal and dendritic NB2a cells. This will include a comparison of the lifetime and turnover rates of the Na+ channel subtypes; 2) To characterize transcripts of mRNA species involved in expression of the two Na+ channel subtypes in differentiated NB2a cells, to determine whether the two Na+ channel subtypes are products of distinct gene species, and to determine the role of mRNA transcription in Na+ channel expression; 3) To establish a model system for studying the reciprocal changes in expression of the two Na+ channel subtypes which occur with innervation and denervation. The major experimental methods used include: 1) characterizing expression of Na+ channel subtypes during NB2a cell differentiation by measurement of high- and low-affinity [3H]- STX receptors; 2) characterizing Na+ channel mRNA species by hybridization with a rat brain Na+ channel II cRNA probe. The health relatedness of the project is that the distribution and function of the various Na+ channel isoforms in normal and abnormal excitable membranes determines the normal physiology and pathophysiology of impulse conduction in these tissues. The NB2a cells provide a model system to begin studying function and distribution of Na+ channel isoforms in excitable membranes. These properties are relevant in : 1) normal function of the nervous system; 2) nervous system diseases such as multiple sclerosis, Alzheimer's disease, and muscular dystrophy; and 3) cardiovascular impulse conduction, arrhythmia generation, and action of anti-arrhythmic agents.