TRANSPORT PROCESSES OF URINARY ACIDIFICATION

尿液酸化的转运过程

• 批准号: 3483575
• 负责人: PHILIP R STEINMETZ
• 金额: $ 17.99万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 1981
• 资助国家: 美国
• 起止时间: 1981-07-01 至 1992-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3483575
• 关键词: Chelonia; Urodela; acetazolamide; acidosis; active transport; adenosinetriphosphatase; aldosterone; anions; apical membrane; bicarbonates; body fluid osmolarity; carbon dioxide; carbonate dehydratase; cell membrane; chlorine; cyclic AMP; cytoskeleton; hormone regulation /control mechanism; hormones; hydrogen transport; ion transport; membrane channels; membrane permeability; parathyroid hormones; passive transport; pinocytosis; urinalysis; urinary bladder; urinary bladder epithelium; urine acidity

The overall organization of urinary acidification has been defined by a variety of studies of the intact kidney and individual nephrons in vivo, yet relatively little is known about the transport processes across the individual cell membranes--their biochemical nature, their rate-limiting factors, and their organization within the epithelial cell layer. The proposed research extends our work on the control of the rate of urinary acidification in the turtle urinary bladder and focuses on the nature of the transport processes across the cell membranes, i.e. the proton pump at the luminal membrane and the efflux of bicarbonate across the serosal membrane. The proton pump characteristics will be analyzed according to a kinetic model consisting of two components: a catalytic unit responsible for active H+ translocation and a membrane channel with a finite resistance to H+ flow. This model simulates the observed relationship between transport rate (JH) and Delta MuH in the linear region and will be tested in the nonlinear regions at large and small Delta MuH. In addition to kinetic factors, JH is regulated by the number of H+ pumps present in the luminal membrane of the carbonic anhydrase(CA) containing cell population. The role of endocytosis and exocytosis will be examined by morphometric techniques during CO2 stimulation of JH with and without agents inhibiting cytoskeletal function. In a combined biochemical and morphologic approach to the isolation of the H+ pumps, we will test the hypothesis that a distinctive rod-shaped intramembrane particle that occurs in abundance in the luminal and vesicular membranes of the CA cells contains components of the H+-translocating ATPase. Freeze fracture studies of membrane fractions will be correlated with the activity of oligomycin- and ouabain-resistant ATPase. In related efforts, we will examine two HC03- transport systems which depend on C1- and occur in the same epithelium, one in series with the H+ pump and one parallel to the H+ pump. The possibility will be explored that the parallel HCO3- secretory system occurs in a subpopulation of CA cells and is composed of the same transport elements in a different arrangement across the two cell membranes. These studies should advance the understanding of the cellular mechanisms of urinary acidification and provide new insights into epithelial acid-base transport in general.

尿酸化的总体组织已由 对体内完整肾脏和单个肾单位的多种研究， 然而，关于跨越的运输过程，相对较少 单个细胞膜 - 他们的生化性质，限制速率 因素及其在上皮细胞层中的组织。 这 拟议的研究扩展了我们在控制尿速率方面的工作 乌龟膀胱中的酸化，专注于 跨细胞膜的运输过程，即质子泵 腔膜和碳酸氢盐跨浆液的外排 膜。 质子泵的特性将根据 动力学模型由两个组成部分组成：催化单元负责 用于主动H+易位和具有有限电阻的膜通道 到H+流动。 该模型模拟了观察到的关系 线性区域中的运输速率（JH）和Delta MUH，将进行测试 在大小的三角洲的非线性区域中。 此外 动力学因素，JH受到H+泵的数量的调节 含碳酸酐酶（Ca）的腔膜，含有细胞群。 内吞作用和胞吞作用的作用将通过形态计量学检查 二氧化碳刺激JH期间有和没有试剂抑制剂的技术 细胞骨架功能。 在生化和形态学方法中 为了隔离H+泵，我们将测试以下假设。 独特的棒状膜内颗粒，发生在丰度中 Ca细胞的腔和囊泡膜包含 H+转移ATPase。 冻结膜分数的断裂研究 将与寡霉素和抗乌巴因的活性相关 ATPase。 在相关的工作中，我们将检查两个HC03运输系统 依赖于C1-发生在同一上皮中，一个与 H+泵，一个与H+泵平行。 可能性将是 探索的是，平行HCO3分泌系统发生在亚群中 CA细胞的，并由不同的运输元素组成 跨两个细胞膜的排列。 这些研究应该进步 对尿酸化和 一般而言，提供有关上皮酸基碱转运的新见解。