REGULATION OF ION PUMPS IN THE RENAL COLLECTING TUBULE

集合管介导活跃的Na+吸收、K+分泌和 H+/HCO3交换。这些过程中的每一个都由离子泵驱动。这个 Na，K-ATPase是E_1-E_2类离子转运型ATPase的成员。 负责生成涉及到的跨上皮梯度 主要由细胞介导的离子通量。E1-E2家族的另一个成员 似乎参与了由 嵌插细胞。肾脏H，K-ATPase已被证明催化 灌流收集中的电中和K+吸收与质子分泌 小管。这两个泵的活动似乎都受到 几种生理刺激。钠泵功能由以下因素调节 醛固酮与[NaI]的变化。肾脏H，K-ATPase升高- 调节对K+耗竭和酸血症的反应。鲜为人知的是 这些影响发挥作用的机制。 最近的证据表明，这些泵的活动是 在转录和跨国后两个层面上都受到控制。 主细胞似乎含有Na，K-APTase池，它们是 保持在静止状态，并可用于快速 动员。肾脏的H，K，-ATPase可能被隔离在 可被诱导与根尖融合的细胞内间隔 质膜。为了了解负责的细胞适应 对于这种反应，有必要建立细胞生物学和 这些泵的生理属性在细胞的上下文中 收集小管。虽然人们已经了解了许多关于生物发生的知识 在培养的细胞系中的离子泵活性，这些 观察结果适用于高分化的 收集小管尚未建立。此外，还研究了 到目前为止，组织培养细胞还不能阐明 控制收集小管特异性调节现象的参数。 我们已经开发了技术和探测器，使我们能够研究 离子泵的特性及其在生理上的调节 相关设置。此应用程序中概述的实验包括 用于1)建立Na，K-ATPase的细胞生物学特性 在急性分离的集合管和主细胞培养中 系统；2)分离出编码肾细胞的c DNA并原位；3) 检测Na，K-ATPase的短期和长期调节及 肾H，K-ATPase在急性分离的集合管和在 主细胞培养体系。了解蜂窝和 参与调节收集功能的分子机制 Tutues的E1-E2离子泵将为 迷人而重要的生理系统。

The collecting tubule mediates active Na+ resorption, K+ secretion and H+/HCO3 exchange. Each of these processes is driven by ion pumps. The Na, K-ATPase, a member of the E1-E2 class of ion transporting ATPase, is responsible for generating the transepithelial gradients involved in principal cell-mediated ion fluxes. Another member of the E1-E2 family appears to participate in the acid-base transport carried out by intercalated cells. The renal H,K-ATPase has been shown to catalyze electroneutral K+ resorption and proton secretion in perfused collecting tubules. The activities of both of these pumps appear to be governed by several physiologic stimuli. Sodium pump function is modulated by aldosterone and alterations in [Nai]. The renal H,K-ATPase is up- regulated in response to K+ depletion and acidemia. Little is known of the mechanisms through which these influences exert their effects. Recent evidence indicates that the activities of theses pumps are controlled at both the transcriptional and post-transnational levels. Principal cells appear to harbor pools of Na,K-APTase which are maintained in a quiescent state and which are available for rapid mobilization. The renal H,K,-ATPase may be sequestered in an intracellular compartment which can be induced to fuse with the apical plasmalemma. In order to understand the cellular adaptions responsible for such responses, it is necessary to establish the cell biologic and physiologic attributes of these pumps in the context of the cells of the collecting tubule. While much has been learned about the biogenesis of ion pump activity in cultured cell lines, the degree to which these observations are applicable to the highly differentiated cells of the collecting tubule has yet to be established. Furthermore, studies on tissue culture cells have, to date, been unable to shed light on the parameters governing collecting tubule-specific regulatory phenomena. We have developed techniques and probes that will allow us to study the properties of ion pumps and ion pump regulation in physiologically relevant settings. The experiments outlined in this application are designed to 1) establish the cell biologic properties of the Na,K-ATPase in acutely isolated collecting tubules and in a principal cell culture system; 2) isolated a cDNA encoding the renal cells and in situ; and 3) examine the short and long term regulation of the Na,K-ATPase and the renal H,K-ATPase in acutely isolated collecting tubules and in the principal cell culture system. An understanding of the cellular and molecular mechanisms involved in governing the function of the collecting tubules's E1-E2 ion pumps will provide valuable insights into a fascinating and important physiologic system.