REGULATION OF RENAL H+/K+ EXCHANGE

肾H/K交换的监管

• 批准号: 2145079
• 负责人: Randi Beth Silver
• 金额: $ 12.07万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 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/2145079
• 关键词: acid base balance; adenosinetriphosphatase; aldosterone; apical membrane; basolateral membrane; electrolyte balance; hydrogen transport; intracellular transport; laboratory rabbit; laboratory rat; membrane transport proteins; perfusion; potassium; renal tubular transport

The cortical collecting tubule (CCT) of the mammalian kidney is responsible for the final regulation of urine pH and potassium (K) concentration. The 2 major cell types involved in this regulation are the Na-transporting principal cells and the acid-base regulating intercalated cells. recent evidence suggests the presence of a gastric- type acid transporter (H-K ATPase) in the renal collecting duct. This proposal focuses on the contribution of a functionally identified H-K exchanger (H-K ATPase) to the process of acid-base and K homeostasis in intercalated cells of the cortical collecting tubule, utilizing fluorescence measurements of intracellular pH and calcium. Six specific aims will be addressed using three related preparations. The functional activity of the H-K exchanger will be monitored by measuring the rate of K-dependent intracellular pH recovery in response to an imposed acid load. the role of this exchanger in K reabsorption and H secretion and regulation by pH, K and aldosterone will be examined. Basic characterization of the H-K exchanger includes assessing the functional similarity of the exchanger to the well-characterized gastric H-K ATPase, apical/basolateral localization of the exchanger, and defining its contribution to intracellular pH regulation under basal conditions. Preparations appropriate to selected aims include: split open cortical collecting tubules, isolated parietal cells, and isolated perfused cortical collecting tubules, loaded with the intracellular pH indicator, BCECF or the intracellular Ca indicator, Fura-2. In addition, the unesterified forms of BCECF and PBFI, a K-specific indicator, will be used for perfused tubule studies. Functional characterization of an H-K exchange mechanism and localization of this mechanism may help explain a number of clinical observations: 1. the association between low serum K and extracellular alkalosis, 2. the relationship between metabolic acidosis and reduced excretion of K which can elevate serum K to a point where it interferes with electrical activity of the heart. The results of these studies will provide important information on normal and pathological K states and will influence our understanding of K balance during metabolic abnormalities and diuretic therapy.

哺乳动物肾脏的皮质收集小管（CCT）是 负责最终调节尿液和钾（K） 专注。 该法规中涉及的两种主要细胞类型是 NA传输主要细胞和调节酸碱 插入的细胞。 最近的证据表明存在胃 在肾脏收集管中型酸转运蛋白（H-K ATPase）。 这 提案重点是功能识别的H-K的贡献 交换器（H-K ATPase）到酸碱和K稳态的过程 皮质收集小管的插入细胞，利用 细胞内pH和钙的荧光测量。 将使用三个相关准备工作来解决六个具体目标。 H-K交换器的功能活动将由 测量响应中K依赖性的细胞内pH恢复速率 施加的酸负荷。 该交换器在K重吸收中的作用 将检查pH，K和醛固酮的H分泌和h分泌和调节。 H-K交换器的基本表征包括评估 交换器与特征良好的胃的功能相似性 H-K ATPase，交换器的顶端/基底外侧定位， 定义其对基础细胞内pH调节的贡献 状况。 适合选定目的的准备工作包括：拆分 开放的皮质收集小管，孤立的顶壁细胞和分离 带有细胞内pH的灌注皮质收集小管 指示器，BCECF或细胞内CA指示器Fura-2。 此外， BCECF和PBFI的未酯化形式（K特异性指标）将 用于灌注小管研究。 H-K交换机制和本地化的功能表征 这种机制可能有助于解释许多临床观察： 1。低血清K与细胞外碱中毒之间的关联，2。 代谢性酸中毒与k的排泄减少之间的关系 可以将血清K提升到干扰电气的点 心脏的活动。 这些研究的结果将提供 有关正常和病态K状态的重要信息，将 影响我们在代谢异常期间对K平衡的理解 和利尿治疗。