ION TRANSPORT BY MAMMALIAN GALLBLADDER EPITHELIAL CELLS

哺乳动物胆囊上皮细胞的离子转运

• 批准号: 6107389
• 负责人: PAMELA J GUNTER-SMITH
• 金额: $ 5.64万
• 依托单位: SPELMAN COLLEGE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6107389
• 关键词: acid base balance; adenylate kinase; apical membrane; basolateral membrane; bicarbonates; calcium flux; cell morphology; cyclic AMP; electrodes; electrophysiology; fluorescent dye /probe; gallbladder; gastrointestinal epithelium; guinea pigs; intracellular transport; ion transport; ionomycin; membrane channels; nucleotides; potassium channel; second messengers; tissue /cell culture; voltage /patch clamp

Studies are proposed to further identify ion transport processes and the factors that regulate them in guinea pig gallbladder epithelial cells. They will initially focus ont he characterization and regulation of influx and efflux pathways for potassium (K+) and bicarbonate (HCO3-). We have postulated that two distinct K+ efflux pathways exist in the apical membrane of guinea pig gallbladder cells based upon the differential sensitivity of transepithelial K+ fluxes to the k+ channel blockers, tetraethylammonium (TEA+) and Charybdotoxin (CHTX). In addition, a quinidine-sensitive, TEA-insensitive pathway has been observed at the basolateral membrane. Our studies will combine transepithelial fluxes, conventional electrophysiology and patch clamp techniques to distinguish the individual K+ efflux pathways underlying these conductances and their physiologic roles. The regulation of K_ transport by cyclic nucleotides, intracellular calcium, and intracellular metabolites such as ATP will be investigated from the effects of the exogenous addition of these agents and appropriate inhibitors on membrane voltage and conductance and single channel characteristics. Measurements of changes in the intracellular concentrations in Ca2+, cAMP and ATP will be correlated with changes in K+ transport. Experiments are also proposed to further define he HCO3- entry step at the basolateral membrane essential for PGE2-stimulated HCO3- secretion. This process appears to be mediate by an electrogenic NaHCO3-cotransproter. Conventional electrophysiologic techniques will be used to define the Na+ and HCO3- dependency of the process, its electrogeneity and its contribution to basolateral membrane conductance. We will initiate studies to determine the intracellular factors regulating its activity from measurements of intracellular pH in cells loaded with fluorescent dyes. The results of these studies will lead to an enhanced understanding of ion transport by the mammalian gallbladder and will be applicable to a variety of other leaky epithelia.

提出了研究以进一步识别离子运输过程和 在豚鼠胆囊上皮细胞中调节它们的因素。 他们最初将集中于涌入的表征和调节 钾（K+）和碳酸氢盐（HCO3-）的外排途径。 我们有 假设顶端存在两个不同的K+外排途径 基于差异的豚鼠胆囊细胞的膜 对K+通道阻滞剂的跨度K+通量的敏感性， 四乙基铵（TEA+）和Charybdotoxin（CHTX）。 另外， 在 基底膜。 我们的研究将结合跨度通量， 传统的电生理学和斑块夹技术以区分 这些电导及其基础的个体K+外排途径 生理角色。 通过环状核苷酸调节K_传输， 细胞内钙和细胞内代谢产物（如ATP）将是 从外源添加这些药物的影响和 膜电压和电导的适当抑制剂以及单个 渠道特征。 测量细胞内变化 Ca2+，CAMP和ATP的浓度将与K+的变化相关 运输。 还提出了实验以进一步定义He HCO3-进入步骤 PGE2刺激的HCO3分泌所必需的基底外侧膜。 这 过程似乎是通过电源NAHCO3-跨跨螺旋体介导的。 常规电生理技术将用于定义Na+ 和HCO3-过程的依赖性，其电性及其依赖性 对基底外侧膜电导的贡献。 我们将开始学习 确定细胞内因子调节其活性从 用荧光染料的细胞中细胞内pH的测量。 这些研究的结果将导致对离子的理解增强 由哺乳动物胆囊运输，将适用于多种 其他泄漏的上皮。