REGULATION OF ION PUMPS IN THE RENAL COLLECTING TUBULE

集合小管介导主动Na+再吸收、K+分泌和 H+/HCO 3交换。 这些过程中的每一个都由离子泵驱动。 的 Na，K-ATPase是E1-E2类离子转运ATP酶的成员， 负责产生跨上皮梯度 主要细胞介导的离子通量。 E1-E2家族的另一个成员 似乎参与了酸碱运输， 闰细胞 肾脏H，K-ATP酶催化 灌流收集中的电中性K ~+吸收和质子分泌 小管 这两个泵的活动似乎都受到 几种生理刺激 钠泵功能通过以下方式调节： [2019 - 01 - 15][2019 - 01][2019 - 01] 肾脏H，K-ATP酶升高- 调节响应K+耗竭和酸血症。 很少有人知道 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 控制在转录和后跨国水平。 主细胞似乎含有Na，K-APTase池， 保持在静止状态，并可用于快速 动员。 肾脏H，K，-ATP酶可能被隔离在一个 细胞内室，其可以被诱导与顶端融合 质膜 为了了解细胞的适应性 对于这种反应，有必要建立细胞生物学， 这些泵的生理属性在细胞的背景下， 集合小管 虽然已经了解了很多关于生物起源的知识， 离子泵活性在培养的细胞系，在何种程度上，这些 观察结果适用于高度分化的细胞， 集合小管尚未建立。 此外，研究 迄今为止，组织培养细胞还不能阐明 控制收集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 生理学中离子泵的性质和离子泵调节 相关设置。 本申请中概述的实验是 设计用于1）建立Na，K-ATP酶的细胞生物学特性， 在急性分离的集合小管和主细胞培养物中 系统; 2）原位分离编码肾细胞的cDNA;和3） 检查Na，K-ATP酶的短期和长期调节， 肾H，K-ATP酶在急性分离的集合小管和在 主要细胞培养系统。 对细胞的理解， 参与控制收集功能的分子机制 tubules的E1-E2离子泵将提供有价值的见解， 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.