MOLECULAR ANALYSIS OF IH CURRENT IN THE NERVOUS SYSTEM

超极化激活的阳离子通道称为I/h，是一种缓慢的内向电流，对钠和钾都是可渗透的。它存在于不同物种的多种细胞类型中，对静息膜电位、神经元放电模式和过度超极化的限制有重要作用。尽管目前已有充分的文献证明了这一重要的生理功能，但仍有许多问题没有得到解答。这些通道的分子组成最近被确定，并属于一个密切相关的基因家族，称为HCN基因家族。这项建议的主要焦点是了解已识别的HCN通道、可能的附加亚单位和自然电流之间的关系。通过核糖核酸酶保护试验和原位杂交确定的HCN通道的表达模式将首先与天然电流的表达进行比较。我们将利用异源表达系统系统地研究同/异构体HCN通道的生物物理和药理学特性，并与天然电流的特性进行比较。不同的HCN通道之间的异构化也将使用免疫共沉淀进行研究。我们将进一步探讨天然通道需要辅助亚单位的假设。这一研究对于进一步研究通道多样性的产生机制以及确定该通道对生理和病理功能的贡献具有重要意义。

The hyperpolarization-activated cation channel called I/h is a slow inward current and permeable to both Na+ and K+. It has been found in a diverse group of cell types in various species and contributes significantly to the resting membrane potential, neuronal firing patterns, and the limitation of excessive hyperpolarization. Although well documented and important physiological functions are known for this current, many unanswered questions remain. The molecular components of these channels have been identified recently and belong to a closely related gene family called the HCN gene family. The major focus of this proposal is to understand the relationships between the identified HCN channels, possible additional subunits, and the native currents. The expression patterns of HCN channels determined by RNase protection assays and in situ hybridization will first be compared to the expression of the native current. The biophysical and pharmacological properties of homo/heteromeric HCN channels will be studied systematically using heterologous expression systems and compared to that of the native currents. The heteromerization among different HCN channels will also be investigated using coimmunopreciptation. The hypothesis that native channels requires an auxiliary subunit will be further explored. This study is essential to further investigate the mechanism generating channel diversity and to determine the contribution of this channel to physiological and pathological function.