TRANSPORT PROCESSES OF URINARY ACIDIFICATION

尿液酸化的转运过程

• 批准号: 3483573
• 负责人: PHILIP R STEINMETZ
• 金额: $ 23.87万
• 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 1995-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3483573
• 关键词: Chelonia; Urodela; acetazolamide; acidosis; active transport; adenosinetriphosphatase; aldosterone; apical membrane; bicarbonates; body fluid osmolarity; carbon dioxide; carbonate dehydratase; cell membrane; chlorine; cyclic AMP; cytoskeleton; hormone regulation /control mechanism; hormones; hydrogen; hydrogen transport; ion transport; membrane permeability; membrane transport proteins; 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 Cl- 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.

尿酸化的整体组织被定义为 对完整肾脏和单个肾单位进行体内的各种研究， 然而，人们对整个运输过程知之甚少。 单个细胞膜——它们的生化性质，它们的速率限制 因素及其在上皮细胞层内的组织。 这 拟议的研究扩展了我们在控制尿率方面的工作 乌龟膀胱的酸化，重点是 穿过细胞膜的运输过程，即质子泵 管腔膜和碳酸氢盐穿过浆膜的流出 膜。 质子泵的特性将根据 动力学模型由两个部分组成：催化单元负责 用于活性 H+ 易位和具有有限电阻的膜通道 至 H+ 流。 该模型模拟了观察到的关系 线性区域的传输速率（JH）和Delta MuH将被测试 在大和小 Delta MuH 的非线性区域中。 此外 动力学因素，JH 受 H+ 泵数量的调节 含有碳酸酐酶（CA）的细胞群的管腔膜。 胞吞作用和胞吐作用的作用将通过形态测量来检查 在使用和不使用抑制剂的情况下对 JH 进行 CO2 刺激期间的技术 细胞骨架功能。 采用生化和形态学相结合的方法 对于 H+ 泵的隔离，我们将检验以下假设： 独特的杆状膜内颗粒，大量存在于 CA 细胞的腔膜和囊泡膜含有以下成分 H+-转位 ATP 酶。 膜组分的冷冻断裂研究 将与寡霉素和哇巴因抗性的活性相关 ATP酶。 在相关工作中，我们将检查两个 HC03- 运输系统 依赖于 Cl- 并发生在同一上皮细胞中，与 H+ 泵和一个与 H+ 泵并联的泵。 可能性将是 探索平行的 HCO3- 分泌系统发生在一个亚群中 CA 细胞，由不同的相同传输元件组成 排列在两个细胞膜上。 这些研究应该推进 了解尿液酸化的细胞机制 为一般上皮酸碱运输提供新的见解。