SINGLE CHANNEL BASIS FOR CAMP DEPENDENT CHLORIDE CURRENT

氯离子转运在盐和液体的分泌中起主要作用 以及对渗透压挑战的响应。 上皮细胞液体分泌 受第二信使cAMP调节。 cAMP的调节- 分泌上皮细胞顶膜依赖性Cl-通道 有助于这些组织中液体分泌的速率决定步骤 细胞 这种cAMP依赖性Cl-转运在囊性纤维化中被破坏 (CF)一种人类遗传病。 几种cAMP依赖性Cl-通道，其活性可能是 宏观Cl-电导，已经在上皮细胞中描述， 在不同的实验条件下。 主要关注的两个渠道 是一个大的（40-45 pS），向外整流的Cl-通道和一个小的（8-10 pS），线性Cl-通道。 这两个通道的活动是 通过cAMP依赖性机制增加。 cAMP- 依赖性单通道和宏观Cl-电流将通过以下方法解决： 问：在细胞膜中可以识别出哪种单一的Cl-通道活性？ cAMP的存在？一种特定的cAMP依赖性单克隆抗体的性质 通道活动占宏观电流的属性？ 这些问题将被解决为同时记录cAMP- 依赖于单个Cl-通道活性和宏观Cl-电流。 一旦 已经鉴定了所涉及的离子通道，它们的选择性， 渗透和动力学特性，以及它们的药理学特性 离子通道将被表征。 cAMP-之间可能的相互作用 和Ca++依赖的第二信使系统的单通道和 还将研究宏观Cl-电流活性。 在广阔的前景，这个项目将解决的生理作用 通过阐明Cl-通道的基本特性和调节 Cl-通道的单通道和宏观机制。 对这些特性的深入了解将有助于弥合 分泌生理学的分子和细胞水平之间的联系。 因此，在本发明中， 通过识别cAMP依赖性Cl-的潜在分子事件， 在上皮细胞中的转运，我们将能够进一步 了解这些离子通道蛋白在流体中的作用 分泌物 这也将提供有价值的洞察机制 囊性纤维化中液体分泌异常的基础。

Chloride transport plays a major role in the secretion of salts and fluids and in response to osmotic challenge. Fluid secretion in epithelial cells is modulated by the second messenger cAMP. The regulation of cAMP- dependent Cl- channels on the apical membrane of secretory epithelia contributes to the rate determining step for fluid secretion in these cells. This cAMP-dependent cl- transport is disrupted in Cystic Fibrosis (CF), a human genetic disease. Several cAMP-dependent cl- channels, whose activity may underlie macroscopic Cl- conductance, have been described in epithelial cells, under different experimental conditions. Two channels of primary interest are a large (40-45 pS), outwardly rectifying Cl- channel and a small (8-10 pS), linear Cl- channel. The activity of both of these channels is increased by cAMP-dependent mechanisms. The relationship between cAMP- dependent single channel and macroscopic Cl- current will be addressed by asking: What single Cl- channel activity can be identified in the presence of cAMP? Can the properties of one specific cAMP-dependent single channel activity account for the properties of the macroscopic current? These questions will be addressed as simultaneously recording cAMP- dependent single Cl- channel activity and macroscopic Cl- current. Once the ion channel(s) involved have been identified, their selectivity, permeation and kinetic properties, and pharmacological profile of their ion channel(s) will be characterized. Possible interactions between cAMP- and Ca++-dependent second messenger systems on single channel and macroscopic Cl- current activity will also be investigated. In the broad prospective, this project will address the physiological role of Cl- channels by elucidating the basic properties and regulatory mechanisms of Cl- channels at the single channel and macroscopic levels. The intimate knowledge of these properties will help to bridge the gaps between the molecular and cellular levels of secretory physiology. Thus, by identifying the underlying molecular events of cAMP-dependent Cl- transport in epithelial cells, we will be able to further the understanding of the role of these ion channel proteins play in fluid secretion. This will also provide valuable insight into the mechanistic basis of abnormal fluid secretion in Cystic Fibrosis.