H+/HCO3- TRANSPORT BY THE COLLECTING DUCT

H /HCO3- 通过收集管运输

• 批准号: 2145048
• 负责人: I. David Weiner
• 金额: $ 6.08万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2145048
• 关键词: acid base balance; adenosinetriphosphatase; apical membrane; basolateral membrane; bicarbonates; immunocytochemistry; intracellular transport; kidney cell; laboratory rabbit; membrane transport proteins; renal tubular transport

The cortical collecting duct (CCD) plays an important role in systemic acid-base homeostasis. Recent studies show the majority of rabbit superficial CCD intercalated cells possess both apical and basolateral plasma membrane C1-/HCO3- exchange. Since this cell has both apical and basolateral C1-?HCO3-, it might be able to either secrete or reabsorb HCO3- and therefore function as either an A cell or B cell. Yet no studies have directly examined the role this cell plays to regulate CCD HCO3- transport. The central hypothesis of this application is that intercalated cell with both apical and basolateral C1-/HCO3- exchange has the capability to transport HCO3-, but that it is not active under normal conditions. When stimulated this cell may be able to either secrete or reabsorb HCO3-. This cell may play a major role in systemic acid-base physiology. Two major aims will examine this hypothesis. the first aim is to characterize the major H+ and HCO3- transporters of this cell. the presence and membrane location of Na+/H+ exchange, H+-ATPase, and H+-K+- ATPase will be determined because of the critical role they play in intracellular pH (pHi) regulation and in HCO3- transport. Apical and basolateral plasma membrane C1-/HCO3- exchange will be compared to C1- /HCO3- exchange in the A cell and B cell because this cell may represent an intermediate intercalated cell, able to function as either an A cell or B cell. The second aim will be to examine the role this cell plays to regulate CCD HCO3- transport. Studies will examine whether this cell can secrete HCO3- and whether it also can reabsorb HCO3-. Finally, we will examine whether in vivo metabolic acidosis and alkalosis induce conversion of this cell into either an A cell or B cell. These studies will measure intracellular pH in individual intercalated cells of in vitro perfused CCD to examine the location and activity of specific HCO3- and H+ transporters. Some experiments will combine this with electron microscopic examination, including immunohistochemical localization of H+-ATPase and C1-/HCO3- exchange, of the same CCD. These techniques will expand our understanding of the mechanisms by which the CCD regulates systemic acid-base homeostasis.

皮质集合管（CCD）在全身系统中发挥着重要作用 酸碱稳态。 最近的研究表明，大多数兔子 表面CCD嵌入细胞同时具有顶端和基底外侧 质膜 C1-/HCO3- 交换。 由于该细胞同时具有顶端和 基底外侧 C1-?HCO3-，它可能能够分泌或重吸收 HCO3- 因此可以充当 A 细胞或 B 细胞。 然而没有 研究直接检验了该细胞在调节 CCD 中的作用 HCO3- 运输。 该应用的中心假设是嵌入细胞 顶端和基底外侧 C1-/HCO3- 交换都有能力 运输 HCO3-，但在正常条件下它不活跃。 什么时候 刺激该细胞可能能够分泌或重吸收 HCO3-。 该细胞可能在全身酸碱生理学中发挥重要作用。 有两个主要目标将检验这一假设。 第一个目标是 表征该细胞的主要 H+ 和 HCO3- 转运蛋白。 这 Na+/H+ 交换、H+-ATP 酶和 H+-K+- 的存在和膜位置 ATPase 将被确定，因为它们在 细胞内 pH (pHi) 调节和 HCO3- 运输。 顶端和 基底外侧质膜 C1-/HCO3- 交换将与 C1- 进行比较 /HCO3- 在 A 细胞和 B 细胞中交换，因为该细胞可能代表 中间嵌入细胞，能够充当 A 细胞 或B细胞。 第二个目标是检查该细胞在调节中所起的作用 CCD HCO3- 传输。 研究将检查该细胞是否可以分泌 HCO3-以及是否也可以重吸收HCO3-。 最后，我们将检查 体内代谢性酸中毒和碱中毒是否会诱导转化 该细胞转化为 A 细胞或 B 细胞。 这些研究将测量个体嵌入细胞内的 pH 值。 体外灌注 CCD 细胞以检查 CCD 的位置和活性 特定的 HCO3- 和 H+ 转运蛋白。 一些实验将结合这一点 电子显微镜检查，包括免疫组织化学检查 同一 CCD 的 H+-ATP 酶和 C1-/HCO3- 交换的定位。 这些 技术将扩大我们对机制的理解 CCD 调节全身酸碱稳态。