MOLECULAR CHARACTERIZATION OF CARDIAC NA+ CHANNELS

哺乳动物电压门控Na+通道由多基因家族编码。 心脏Na+通道与该家族的关系目前尚不清楚。 未知其他可兴奋组织中的“TTX抗性”心脏NA+通道。 目前的证据表明，心脏Na+通道最有可能编码 由这个多基因家族中未被发现的基因组成。广泛的长期 这些研究的目的是：1）确定在何种程度上， 心脏Na+通道的特殊功能特性是 由不同的基因序列或由其他修饰的 已知的Na+通道基因。2)为了表征不同的分子 心脏Na+通道的结构， 专门的功能特性。3)为了进一步阐明 与心脏Na+相比，多基因家族的其他成员 渠道。4)确定控制心脏Na+通道的机制 表达，包括那些参与差异表达的 在其各自的组织中存在多种Na+通道亚型。具体 实现这些目标的目的和实验设计是：1）生成 从P6大鼠心脏的质粒或噬菌体cDNA文库中， 这些文库含有来自大鼠脑Na通道11的cRNA探针， 顺序2)分析; 3）确定发展，区域和 心肌Na+的组织特异性表达和功能特性 通道mRNA。4)构建全长cDNA并在大肠杆菌中表达， 包括非洲爪蟾卵母细胞和转染的哺乳动物的异源系统 细胞，以确定哪些专门的功能特性的心脏钠 通道由心脏Na+通道的不同序列编码 α亚基这项工作的健康相关意义在于， 正常和异常心脏冲动传导的分子基础将是 阐明，并为设计更特异性的抗- 确定了药物。

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.