ISOLATED COLLECTING TUBULE CELLS--ION TRANSPORT

哺乳动物肾单位的集合管系统起着至关重要的作用， 调节水和电解质平衡。 其蜂窝 然而，异质性极大地阻碍了描述 运输过程及其在细胞水平上的调节。 细胞 P.I.最近开发的特异性单克隆抗体。现在已经 使分离和培养单个细胞类型成为可能。 免疫吸附和荧光激活细胞法集合管 分选并研究这些细胞的运输特性。 原代培养物 闰细胞（ICC）和主细胞（PC），显示 分化功能，如分泌H+和K+， Na+、PO 4和Ca 2+的重吸收，可以维持在渗透性的 支持. 这样的文化也保留了他们原来的荷尔蒙 反应性，并表达许多抗原，他们在原位。 通过这些技术获得的初步结果提供了基础， 该项目的长远目标是阐明（1） PC分泌K+的机制;（2）ICC在酸碱平衡中的作用 稳态，目的（1）提出了细胞的详细分析， AVP对PC单层K+分泌的作用机制。 这些 研究将探讨AVP对血管内皮细胞具有双重作用的可能性。 PC通过cAMP和细胞内Ca 2+信使系统， 检查K+渗透性变化的贡献， 在AVP作用机制中对K+的驱动力。 第1102章目的（二） 还将测试K+本身可以调节K+的可能性。 分泌引起适应性变化，醛固酮调节 这个回应。 目的（2）研究H+的作用机理 培养的ICC分泌。 具体来说，我们将研究 顶端H+-ATP酶对酸分泌的贡献， 确定涉及的机制，通过基地处置 基底外侧膜 最后，我们将测试醛固酮的作用 离子组成的变化类似于 代谢性/呼吸性水肿和酸中毒。 新的信息 这些研究所获得的信息应该有助于阐明 通过远端肾单位控制肾K+分泌和酸化， 从而更好地理解了 酸碱平衡和钾平衡紊乱。

The collecting duct system of the mammalian nephron plays a critical role in regulating water and electrolyte balance. Its cellular heterogeneity, however, has greatly hampered attempts to characterize transport processes and their regulation at the cellular level. Cell specific monoclonal antibodies recently developed by the P.I. have now made it possible to isolate and cluture individual cell types of the collecting duct by immunoadsorption and fluorescence-activated cell sorting and study transport properties of these cells. Primary cultures of intercalated cells (ICC) and principal cells (PC), displaying differentiated functions, such as secretion of H+ and K+ and reabsorption of Na+, PO4, and Ca2+, can be maintained on permeable supports. Such cultures also retain their original hormonal responsiveness and express many of the antigens they posses in situ. Preliminary results obtained by these techniques provide the basis for the long-term objectives of this project, which are to elucidate (1) the mechanism of K+ secretion by PC; and (2) the role of ICC in acid-base homeostasis, Aim (1) proposes a detailed analysis of the cellular mechanism of the action of AVP on K+ secretion in PC monolayers. These studies will address the possibility that AVP exerts a dual action on PC, through the cAMP and intracellular Ca2+-messengers systems and will examine the contribution of alterations in K+ permeability and changes in driving forces for K+ in the mechanism of action of AVP. Aim (2) will also test for the possibility that K+ itself can modulate K+ secretion by causing adaptive changes, and that aldosterone modulates this response. Aim (2) involves a study of the mechanism of H+ secretion by cultured ICC. Specifically, we will examine the contribution of an apical H+-ATP-ase to acid secretion and will determine the mechanisms involved in base-disposal through the basolateral membrane. Finally, we will test the effect of aldosterone and changes in ion composition resembling those seen during metabolic/respiratory alkalosis and acidosis. The new information acquired by these studies should help to clarify the mechanisms controlling renal K+ secretion and acidification by the distal nephron, and consequently, lead to a better understanding of the etiology of the disturbances of acid-base and potassium homeostasis.