MECHANISM OF NA+-DEPENDENT METABOLITE TRANSPORT

NA依赖性代谢物转运机制

• 批准号: 3225374
• 负责人: GEORGE A KIMMICH
• 金额: $ 14.8万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-03-01 至 1992-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3225374
• 关键词: adenosine triphosphate; aminoacid transport; bioenergetics; carbohydrate sequence; carbohydrate transport; electrophysiology; gastrointestinal epithelium; ion transport; mathematical model; membrane model; membrane permeability; membrane potentials; nonelectrolyte transport; radiotracer; tissue /cell culture

This proposal is aimed at the development of new methodology for rapid noninvasive measurement of cellular membrane potentials and use of these methods to characterize the Delta Psi dependence of a variety of plasma membrane related transport events. Isolated intestinal epithelial cells prepared from chickens will continue to be the primary model experimental system. The work described falls in three broad categories: 1) establishment of the relationship between unidirectional influx of tetraphenylphosphonium (TPP+) and Delta Psi for use as a calibration curve in defining unknown membrane potentials, 2) a systematic study of the quantitative relationship between Delta Psi and Na+-dependent sugar or amino acid transport processes, and 3) identification of the cellular "signals" and mode of action of those agents which are important in allowing intestinal tissue to convert from its normal absorptive functional state for salt and water to a secretory state resulting in the symptoms of diarrhea. The Delta Psi-sugar transport relationships will be used to discriminate between transport models involving Delta Psi-dependent translocation vs. Delta Psi-dependent Na+ binding events as a means of evaluating a "Na+-well" conceptual model which has not yet been tested experimentally. The possibility that Na+-dependent transport systems can be used as intrinsic sensors for noninvasive quantitative measurement of membrane potentials will also be evaluated. Finally, the methods established will be applied to a characterization of the specific ion flux pathways altered in activity by Ca++, cAMP, and certain hormones or drugs with particular emphasis on correlating changes in cellular transport activity with concomitant changes in the appropriate "signal" molecule or ion. The endeavor offers an opportunity for providing some of the first mechanistic insight to the quantitative role which membrane potentials play in driving Na+-dependent transport systems as well as insight to the mechanisms by which the intestinal epithelium converts from absorptive to secretory activity for salt and water and the regulation of the ion transport pathways involved. This insight carries significant clinical ramifications because of the enormous impact diarrheal diseases have as world-wide health problems.

该建议旨在制定新的方法， 细胞膜电位的非侵入性测量及其应用 表征各种等离子体的Δ Psi依赖性的方法 膜相关的运输事件。 分离的肠上皮细胞 从鸡制备的将继续是主要的模型实验 系统 福尔斯所描述的工作分为三大类： 建立单向流入的 四苯基鏻（TPP+）和Δ Psi用作校准曲线 在定义未知的膜电位，2）一个系统的研究， Δ Psi和Na+依赖性糖或 氨基酸转运过程，和3）细胞的鉴定 “信号”和这些药物的作用方式，这是重要的， 使肠组织从其正常的吸收功能 盐和水的分泌状态导致的症状 腹泻 Delta Psi-糖运输关系将用于 区分涉及Delta Psi依赖的运输模型 易位与Δ Psi依赖性Na+结合事件作为 评估尚未测试的“Na+井”概念模型 实验性的 Na+依赖性转运系统可能 用作非侵入性定量测量的内在传感器， 还将评估膜电位。 最后，方法 建立将适用于表征的具体离子通量 通过Ca++、cAMP和某些激素或药物改变活性的途径 特别强调细胞运输的变化 活性伴随适当“信号”分子的变化，或 离子。 这一奋进提供了一个机会， 对膜电位所起的定量作用的机械见解 在驱动Na+依赖的运输系统以及洞察 肠上皮细胞从吸收性转化为 盐和水的分泌活动以及离子的调节 涉及的运输途径。 这一见解具有重要的临床意义 由于疟疾疾病的巨大影响， 全球性的健康问题。