REGULATION OF INTRACELLULAR PH IN RENAL PROXIMAL TUBULE

肾近端小管细胞内 PH 值的调节

• 批准号: 2138363
• 负责人: Walter F. Boron
• 金额: $ 32万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1982
• 资助国家: 美国
• 起止时间: 1982-01-01 至 1994-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2138363
• 关键词: Urodela; acid base balance; acidity /alkalinity; alternatives to animals in research; apical membrane; basolateral membrane; bicarbonates; cell type; fluorescence spectrometry; fluorescent dye /probe; hydrogen; hydrogen transport; intracellular transport; laboratory rabbit; membrane permeability; membrane transport proteins; parathyroid hormones; renal tubular transport; renal tubule; sodium

This proximal tubule (PT) is the major site of HCO3, reabsorption/acid secretion in the mammalian kidney. Although the classical model of PT acid secretion includes only a Na-H exchanger at the luminal membrane of the PT cell and a pathway for HCO3 exit at the basolateral (i.e., blood-side) membrane, we now know that this is an oversimplification in two respects. First, numerous acid-base transporters have been identified in PT cells. Nevertheless, several of these remain to be characterized. Second, there are important qualitative and quantitative differences in acid-base transport among PT cells, based upon both distance along the nephron from the glomerulus (i.e., S1 vs. S2 vs. S3 segments) and the location of the glomerulus giving rise to the tubule (i.e., superficial, SF vs. juxtamedullary, JM). Understanding PT acid-base physiology will require a systematic characterization of each acid-base transpor-ter in each of the six PT subtypes (SF S1-S3, JM S1-S3), a task that has just begun. We propose to continue our characterization of intracellular pH(pHi) regulation and acid-base transporter in experiments on isolated perfused rabbit PTs. pHi will be continuously monitored by loading the cells with a pH-sensitive dye, illuminating a small number of cells with a 10-mu m- diameter beam of light, and measuring either the dye's absorbance or fluorescence. We will assess individual acid-base transporters by monitoring the recovery of pHi from acute acid or alkali loads, or by monitoring rates of pHi change after other perturbations. One aim is to examine the properties of acid-base transporters that are not well characterized in intact tubules, initially employing only one PT subtype (e.g., SF S3). These transporters include monocarboxylate cotransporters; the Na/HCO3 cotransporter in the S3 segment; transporters or inorganic phosphate, amino acids and other solutes; and the novel alkalizing process activated by basolateral HCO3, in the S3 segment. Our second aim is to conduct a systematic and comprehensive survey of each established PT acid- base transporters in each of the six PT subtypes. Our third aim is to analyze the effects of angiotensin II and other agents not only on luminal Na-H exchange and basolateral Na/HCO3 cotransport, but on the whole ensemble of transporters that affect pHi in the PT. Finally, our fourth aim is to use newly available Na+-sensitive dyes (and possibly voltage- sensitive dyes) to study Na+- (and voltage-) coupled acid-base transport in the rabbit PT. The proposed work will provide a comprehensive description of acid-base transport throughout the PT. The use of isolated, perfused tubules will insure that the expression of the transporters is as normal as possible, and that anatomical origin of the tubules is precisely known.

该近端小管（PT）是HCO3的主要部位，吸收/酸 哺乳动物肾脏的分泌。 虽然PT酸的经典模型 分泌仅包括PT的腔膜上的NA-H交换器 细胞和HCO3出口的途径（即血液侧） 膜，我们现在知道这是两个方面的过度简化。 首先，在PT细胞中已经鉴定出许多酸碱转运蛋白。 然而，其中几个仍有待描述。 第二，那里 是酸碱的重要定性和定量差异 基于沿着肾单位的两个距离之间的PT细胞之间的运输 肾小球（即S1 vs. S2 vs. S3段）和位置 肾小球引起小管（即表面，sf vs。 Juxamedullary，JM）。 了解PT酸碱生理学将需要 每个酸碱转运ter的系统表征 六个PT子类型（SF S1-S3，JM S1-S3），这项任务刚刚开始。 我们 建议继续我们对细胞内pH（PHI）的表征 在分离的灌注的实验中调节和酸碱转运蛋白 兔子Pts。 PHI将通过将细胞加载A加载A加载 pH敏感的染料，用10 mu m-照亮少数细胞 光束光束，并测量染料的吸光度或 荧光。 我们将通过 监测急性酸或碱负荷中的PHI的回收，或者通过 其他扰动后的PHI变化速率。 一个目的是 检查酸碱转运蛋白的性质不好 以完整的小管为特征，最初仅采用一种PT亚型 （例如SF S3）。 这些转运蛋白包括单羧酸盐共转运蛋白； S3段中的Na/Hco3共转运蛋白；转运蛋白或无机 磷酸盐，氨基酸和其他溶质；和新颖的碱化过程 在S3段中被基底外侧HCO3激活。 我们的第二个目标是 对每个已建立的PT酸 - 进行系统，全面的调查 六个PT亚型的每个基础转运蛋白。 我们的第三个目标是 分析血管紧张素II和其他药物对腔的影响 NA-H交换和基底外侧Na/Hco3共晶，但总体而言 影响PT中PHI的转运蛋白的合奏。 最后，我们的第四个 目的是使用新近可用的Na+敏感染料（可能是电压 - 敏感染料）研究Na+ - （和电压 - ）偶联的酸碱转运 兔子Pt。 拟议的工作将提供全面的描述 整个PT的酸碱转运。 使用孤立，灌注 小管将确保转运蛋白的表达与 可能是可能的，并且小管的解剖学起源是众所周知的。