CHLORIDE CHANNELS AND GASTRIC ACID SECRETION

胃溃疡的治疗控制有赖于干预 它们控制着盐酸的分泌。它的广泛、长期目标是 提案是定义参与调控的分子和机制 胃酸分泌物。而ATP为依赖于镁的钾提供燃料。 依赖和H转运的胃H/K ATPase(EC 1.2.1.26)，盐酸 H/K-ATPase的产生还需要K和Cl-从 胞浆穿过顶膜到达分泌小管。K是一种 H/K-ATPase底物和Cl-为HCl提供等价物 制作。胃壁细胞顶膜的离子转运 受cAMP依赖的蛋白激酶控制。这些通道起作用 在pH为3或更低的严酷但生理相关的条件下 沐浴在海峡的胞外面。一种酸和电压 激活的氯离子通道已经被鉴定、克隆和表达，并且一种 在过去的三年中，酸性稳定的钾通道也得到了表征 资助期。事实证明，这些渠道本身就是 CAMP依赖的蛋白激酶。对盐酸蓄积的体外激活作用 分离的胃小泡也已被证实。世界银行的目标是 目前的建议是进一步阐明这些新的 胃壁细胞分泌的氯离子和钾离子通道的发现 调节HCl分泌的膜。建议的研究是必不可少的。 了解与生理相关的控制盐酸的机制 分泌物。作为主要的工作假说，离子的活动性 壁细胞分泌膜的通道是一种主要的 哺乳动物体内HCl分泌调节的靶标。这次会议的重点是 本申请旨在了解这些离子是如何 通道在调节HCl的分泌中起作用。具体目标是 因此，对L来说)比较和对比电生理特性 具有宏观K、Cl-通量和H的通道 积累。2)确定了酸的调节机制和 电压调节氯离子通道来自天然来源和重组来源。 对新发现的K通道的调节也将被研究。 确定《公约》独特监管方面的结构基础 CL频道。4)确定氯离子通道的定位位置 胃粘膜内的细胞和氯离子通道的分布 在壁细胞内处于非分泌和分泌状态；5) 检查胃氯离子通道是由一种 C1C-2基因的选择性剪接转录本。这些研究提供了 重要的分子和机制与生理细胞和 对HCl分泌的整体动物研究，并可能为 了解细胞和分子机制的基础 由上皮细胞调节分泌。

Therapeutic control of gastric ulcer disease relies upon interventions which control HCl secretion. The broad, long term objectives of this proposal are to define the molecules and mechanisms involved in regulation of gastric HCl secretion. Whereas ATP fuels the Mg2+-dependent, K+- dependent and H+-transporting gastric H/K ATPase (EC 1.2.1.26), HCl production by the H/K ATPase also requires K+ and Cl- passage from the cytosol across the apical membrane to the secretory canaliculus. K+ is a substrate for the H/K ATPase and Cl- provides equivalents of Cl- for HCl production. Ion transport across the gastric parietal cell apical membrane is under control by cAMP dependent protein kinase. These channels function under the harsh, but physiologically relevant condition of pH 3 or lower bathing the extracytosolic face of the channel. An acid and voltage activated Cl- channel has been characterized, cloned and expressed, and an acid stable K+ channel has also been characterized during the past 3 year funding period. The channels have been shown to be targets, per se, of cAMP dependent protein kinase. In vitro activation of HCl accumulation by isolated gastric vesicles has also been demonstrated. The goals of the present proposal are to further elucidate the role of these newly discovered Cl- and K+ channels of the gastric parietal cell secretory membrane in regulated HCl secretion. The proposed studies are essential to understanding the physiologically relevant mechanisms of control of HCl secretion. As the major working hypothesis, the activity of the ion channels of the secretory membrane of the parietal cell represent a major target of the regulation of HCl secretion in mammals. The focus of the present application is directed toward understanding how these ion channels function in regulated HCl secretion. The specific aims are therefore to l) Compare and contrast the electrophysiological properties of the channels with macroscopic measures of K+ and Cl- flux and H+ accumulation. 2) Determine the mechanisms of regulation of the acid and voltage regulated Cl- channel from native and recombinant sources. Regulation of the newly identified K+ channel will also be studied 3) Determine the structural basis for the unique regulatory aspects of the Cl- channel. 4) Determine the sites of localization of the Cl- channel to cells within the gastric mucosa, and the distribution of the Cl- channels within the parietal cell in the non-secreting and secreting state and; 5) Examine the hypothesis that the gastric Cl- channel is encoded by an alternatively spliced transcript of the C1C-2 gene. These studies provide important molecular and mechanistic links with physiological cellular and whole animal studies of HCl secretion and may provide a paradigm for understanding the cellular and molecular mechanisms which underlie regulated secretion by epithelia.