MECHANISM OF NA+-DEPENDENT METABOLITE TRANSPORT

NA依赖性代谢物转运机制

• 批准号: 3225379
• 负责人: GEORGE A KIMMICH
• 金额: $ 11.79万
• 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 1987-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3225379
• 关键词: adenosine triphosphate; aminoacid transport; bioenergetics; carbohydrate transport; electrophysiology; gastrointestinal epithelium; ion transport; membrane model; membrane permeability; membrane potentials; nonelectrolyte transport; radiotracer; solute; tissue /cell culture

This project is oriented toward evaluating the mechanistic role for cellular membrane potential as a part of the driving force for intestinal Na ion - dependent transport systems. The evaluation depends on employing isolated intestinal epithelial cells as an experimental model which offers unusual experimental advantages relative to intact tissue models. These include: 1) selective control of mucosal and serosal sugar transport systems, 2) accurate definition of gradient forming capability for Na ion-dependent systems, 3) opportunity for steady-state kinetic analysis of transport fluxes, 4) limitation of tight-junctional and other non-cellular flux pathways, and 5) methods for independent control of cellular chemical potentials for Na ion and electrical potentials and hence opportunity for exploring the role for each in maintaining transport capability. The work encompasses effort aimed at development of methods for utilization of carbocyanine dyes and hydrophobic cations for noninvasive measurement of membrane potentials. Recent work has emphasized limitations in usual procedures for measuring Na ion:sugar coupling stoichiometries and provided information that the true coupling stoichiometry is 2Na ion per sugar molecule. Work in the coming year will focus on experiments which will help distinguish between various transport models involving 2Na ion ions per carrier cycle. Other work will be aimed at defining the extent to which a diffusional flux route for sugar limits the steady-state gradient forming capability of the Na ion-dependent carrier and the mechanistic basis for regulation of Na ion-dependent transport by exogenous ATP.

该项目是面向评估细胞的机制作用， 膜电位作为肠钠离子驱动力的一部分， 依赖运输系统。 评估取决于使用隔离的 肠上皮细胞作为一个实验模型，提供了不寻常的 相对于完整组织模型的实验优势。 这些措施包括：1） 选择性控制粘膜和血清糖转运系统，2）准确 Na离子依赖系统的梯度形成能力的定义，3） 输送通量的稳态动力学分析的机会，4）限制 紧密连接和其他非细胞通量途径的方法，和5）用于 Na离子和电化学势独立控制 潜力，因此有机会探索每个人在维护 运输能力。 这项工作包括努力发展 利用碳菁染料和疏水阳离子 膜电位的非侵入性测量。 最近的工作强调了测量钠的常规程序的局限性 离子：糖耦合化学计量，并提供了信息，真正的 偶联化学计量比为每个糖分子2个Na离子。 来年工作 将专注于有助于区分各种运输方式的实验， 涉及每个载体循环2Na离子的模型。 其他工作将针对 限定糖的扩散通量路径限制糖的扩散通量的程度， Na离子依赖性载体的稳态梯度形成能力和 外源性ATP调节Na离子依赖性转运的机制基础。