MECHANISM OF NA+-DEPENDENT METABOLITE TRANSPORT

这项建议旨在为RAPID开发新的方法学 细胞膜电位的非侵入性测量及其应用 表征多种血浆的增量Psi依赖关系的方法 与膜相关的运输事件。分离的肠上皮细胞 由鸡制备的模型将继续作为主要的实验模型 系统。所描述的工作分为三大类：1) 建立单向人流与人流之间的关系 用作校准曲线的四苯基膦(TPP)和Delta Psi 在定义未知的膜电位时，2)系统地研究 DELTA Psi与钠依赖糖OR的定量关系 氨基酸转运过程，以及3)细胞鉴定 “信号”和行动模式的那些代理人是重要的 允许肠道组织从其正常的吸收功能 盐分和水的状态变为分泌状态，导致 拉肚子。Delta Psi-糖运输关系将用于 依赖于Delta Psi的输运模型的辨析 易位与依赖Delta Psi的钠结合事件作为一种手段 评估一个尚未经过测试的“纳井”概念模型 试验性的。依赖钠的运输系统可能会 可作为本征传感器用于非侵入式定量测量 还将对膜电位进行评估。最后，提出了几种方法 将应用于特定离子通量的表征 被钙、cAMP和某些激素或药物改变的活性通路 特别强调细胞运输的相关变化 伴随适当的“信号”分子的变化的活性或 离子。这一努力提供了一个机会，可以提供一些第一 膜电位定量作用的机械论洞察 推动依赖钠的运输系统以及对 肠上皮细胞从可吸收转化为 盐分和水分的分泌活性与离子调节 涉及的运输路径。这一见解具有重要的临床意义。 分叉，因为腹泻疾病具有巨大的影响 世界性的健康问题。

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.