REGULATORY MECHANISMS OF CARDIAC REPOLARIZATION

电压门控离子通道亚型的差异表达和 单通道同种型数量的变化是两种机制， 可以调节心脏动作电位。 电压-门控K+ 离子通道是心脏中最复杂的离子通道 并在心肌细胞膜复极过程中起着重要作用。 动作电位 本申请中概述的研究将集中在 对存在于细胞中的电压敏感性钾通道的调节 哺乳动物心脏 七个不同的K+通道已经被克隆， 这个实验室从老鼠和人的心脏。 为了将这些 克隆通道与天然肌细胞电流，免疫组织化学将 在组织切片上用目前存在的抗体进行， 生产中的抗血清。 此外，K+通道的识别 在最近可用的心房细胞系中表达的同种型将 将钾通道结构与心房钾电流相关联。 是否这些 同种型在完整的心脏中或在心脏中组装成异源四聚体。 将确定心房细胞系。 没有关于 细胞维持适当数量的细胞表面K+的机制 渠道 因此，细胞调节机制负责 维持细胞表面K+的生理正确数量 将使用组织培养表达系统检查通道。 在确定5'和3'未翻译的调节作用后， 序列，通道生物合成和细胞内的基本参数 运输将使用脉冲追踪技术和抗体进行检查 基于亲和纯化。 C末端氨基酸的作用 在生物合成、亚基组装和细胞内靶向中的作用将 也要检查。 由于电压门控钾通道表达 在心脏中的许多可兴奋组织中发现，这项研究将 显著影响心脏钾离子通道的外场 physiology.

Differential expression of voltage-gated ion channel isoforms and variation in the number of a single channel isoform are two mechanisms by which the cardiac action potential can be regulated. Voltage-gated K+ channels represent the most complex group of ion channels in the heart and play a central role in cardiac membrane repolarization during the action potential. The research outlined in this application will focus on the regulation of voltage-sensitive potassium channels present in mammalian heart. Seven distinct K+ channels have already been cloned by this laboratory from rat and human heart. In order to correlate these cloned channels with native myocyte currents, immunohistochemistry will be performed on tissue sections with antibodies that currently exist and antisera under production. In addition, identification of the K+ channel isoforms expressed in a recently available atrial cell line will correlate K+ channel structure with atrial K+ currents. Whether these isoforms assemble into heterotetramers in the intact heart or in the atrial cell line will be determined. No information exists on the mechanisms by which a cell maintains the proper number of cell surface K+ channels. Therefore, the cellular regulatory mechanisms responsible for maintaining the physiologically correct number of cell surface K+ channels will be examined using a tissue culture expression system. Following determination of the regulatory role of 5' and 3' untranslated sequence, the basic parameters of channel biosynthesis and intracellular transport the will be examined using pulse-chase techniques and antibody based affinity-purification. The role that the C-terminal amino acids play in biosynthesis, subunit assembly and intracellular targeting will also be examined. Since the voltage-gated potassium channels expressed in the heart are found in many excitable tissues, this research will have significant impact outside the field of cardiac potassium channel physiology.