REGULATION OF RENAL H+/K+ EXCHANGE

肾H/K交换的监管

• 批准号: 3464812
• 负责人: Randi Beth Silver
• 金额: $ 10.57万
• 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/3464812
• 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集合管 (CCT) 是 负责尿液 pH 值和钾 (K) 的最终调节 专注。 参与此调节的两种主要细胞类型是 输钠主细胞与酸碱调节 闰细胞。 最近的证据表明存在胃- 肾集合管中的酸性转运蛋白（H-K ATP酶）。 这 提案重点关注功能确定的 H-K 的贡献 交换器（H-K ATP酶）对酸碱和钾稳态过程的影响 皮质集合管的嵌入细胞，利用 细胞内 pH 值和钙的荧光测量。 将通过三项相关准备工作来实现六个具体目标。 H-K 交换器的功能活动将通过以下方式进行监控 测量响应中 K 依赖的细胞内 pH 恢复率 施加的酸负荷。 该交换器在钾重吸收中的作用 将检查 H 的分泌以及 pH、K 和醛固酮的调节。 H-K 交换器的基本特性包括评估 交换器与充分表征的胃的功能相似性 H-K ATP酶，交换器的顶端/基底外侧定位，以及 定义其在基础条件下对细胞内 pH 调节的贡献 状况。 适合选定目标的准备工作包括： 打开皮质集合管，分离壁细胞，分离 灌注皮质集合管，负载细胞内 pH 值 指示剂 BCECF 或细胞内 Ca 指示剂 Fura-2。 此外， BCECF 和 PBFI 的非酯化形式（K 特定指示剂）将 用于灌注小管研究。 H-K 交换机制的功能表征和定位 这种机制的研究可能有助于解释一些临床观察结果： 1. 低血清 K 与细胞外碱中毒之间的关联，2. 代谢性酸中毒与钾排泄减少的关系 它可以将血清 K 升高到干扰电的程度 心脏的活动。 这些研究的结果将提供 有关正常和病理 K 状态和意志的重要信息 影响我们对代谢异常期间钾平衡的理解 和利尿疗法。