MOLECULAR CHARACTERIZATION OF CARDIAC NA+ CHANNELS

哺乳动物电压门控钠通道是由一个多基因家族编码的。 心脏钠通道(S)与这个家族的关系目前 未知。在其他可兴奋组织中存在抗TTX的心脏NA通道。 目前的证据表明，心脏钠通道(S)很可能编码 由这个多基因家族中的未被发现的基因。宽泛的长期 这些研究的目标是：1)确定在何种程度上 心脏钠通道的特殊功能特性(S)是 由不同的基因序列或由其他修改的 已知的钠通道基因。2)表征不同的分子 心脏钠通道的结构(S)，解释了这些 特殊的功能特性。3)进一步阐明的性质 多基因家族的其他成员与心肌钠的比较 频道(S)。4)确定心肌钠通道的调控机制 表达，包括参与差异表达的那些 在它们各自的组织中有多种钠通道亚型。具体的 实现这些目标的目标和实验设计是：1)生成 P6大鼠心脏质粒库或噬菌体文库的构建及筛选 这些文库带有来自大鼠脑钠通道11的cRNA探针 序列。2)分析；3)确定发展、区域和 心肌钠的组织特异性表达及其功能特性 通道mRNAs。4)构建全长cDNA并在 包括非洲爪哇卵母细胞和转基因哺乳动物的异源系统 细胞，以确定心肌钠的哪些特殊功能特性 通道由心脏钠通道的不同序列编码 阿尔法亚单位。这项工作与健康相关的意义在于 心脏冲动传导正常和异常的分子基础将是 阐明了其分子基础，为设计更具特异性的抗病毒药物奠定了基础 心律失常药物已确定。

Mammalian voltage-gated Na+ channels are encoded by a multigene family. The relationship of cardiac Na+ channel(s) to this family is currently unknown. "TTX- resistant" cardiac NA+ channels in other excitable tissue. Current evidence suggests that cardiac Na+ channel(s) most likely encoded by undiscovered genes within this multigene family. The broad long-term objectives of these studies are: 1) To determine to what extent the specialized functional properties of the cardiac Na+ channel(s) are accounted for by distinct gene sequences or by other modifications of known Na+ channel genes. 2) To characterize the distinct molecular structures of the cardiac Na+ channel(s) which account for these specialized functional properties. 3) To further elucidate properties of other members of the multigene family by comparison with the cardiac Na+ channel(s). 4) To determine mechanisms controlling cardiac Na+ channel expression, including these involved in differential expression of multiple Na+ channel isoforms in their respective tissues. The specific aims and experimental design to achieve these goals are: 1) To generate plasmid or bacteriophage cDNA libraries from P6 rat heart, and to screen these libraries with cRNA probes from the rat brain Na channel 11 sequence. 2) To analysis; 3) To determine the developmental, regional and tissue specific expression and functional properties of cardiac Na+ channel mRNAs. 4) To construct full-length cDNAs and to express them in heterologous systems including Xenopus oocytes and transfected mammalian cells, to determine which specialized functional properties of cardiac Na channels are encoded by the distinct sequence of the cardiac Na+ channel alpha-subunit. The health-related significance of this work is that the molecular basis of normal and abnormal cardiac impulse conduction will be elucidated, and a molecular basis for the design of more specific anti- arrhythmic agents determined.