ACID-BASE TRANSPORT IN INNER MEDULLARY COLLECTING DUCTS

这项建议旨在研究分布，机制， 大鼠内髓H/HCO_3转运的调节 集合管（IMCD）。 以前的研究已经确定， IMCD是尿酸化和净酸的主要部位 分泌物 最近的形态学和功能研究 广泛研究了H/HCO 3的机制和调节 在皮质和外髓集合管中运输。 的 IMCD以前没有通过体外微灌注进行研究 因为它的技术难度。 由于最近一些 技术的进步，现在可以剖析IMCD， 无菌动物 我们将在体外分离和灌注IMCD，使我们能够（1） 确定H/HCO 3传输沿着 IMCD;（2）使用荧光标记识别转运机制 测量细胞pH值;（3）确定分泌的细胞类型 质子与荧光和光学显微镜;和（4）确定 使用所有的跨上皮转运的调节机制 以上技术。 这些研究将提供深入了解 途径，介导质子分泌的终端部分， 肾单位，并将提供一个更好的理解的作用， IMCD对肾酸碱平衡的影响。 我在国家卫生研究院和莫里斯布尔格博士一起进行博士后培训时， 我学习了体外微灌注技术， 荧光显微镜，我用这些来研究 HCO 3和氨在近端小管中的转运和收集 风管段。 这些技术已经成功地转移到 我在西南医学院的新实验室 我现在将 应用这些技术（沿着更灵敏的测定总 我专门为这些研究开发的CO2），以解决 大鼠内髓集合管存在上述问题。 我的担保人罗伯特·阿尔珀恩医生在 在近端小管中进行类似的研究， 广泛参与这些研究的监督。 此外，博士。 唐纳德·塞尔丁，他长期以来对远端 酸化，也将涉及。

This proposal seeks to study the distribution, mechanism, and regulation of H/HCO3 transport in the rat inner medullary collecting duct (IMCD). Previous studies have established that the IMCD is a major site of urinary acidification and net acid secretion. Recent morphologic and functional studies have extensively examined the mechanisms and regulation of H/HCO3 transport in the cortical and outer medullary collecting duct. The IMCD has not been studied previously by in vitro microperfusion because of its technical difficulty. Due to a number of recent technical advances, it is now possible to dissect the IMCD from germ-free animals. We will isolate and perfuse the IMCD in vitro permitting us to (1) determine the axial distribution of H/HCO3 transport along the IMCD; (2) identify the mechanism of transport using fluorescent measurements of cell pH; (3) identify the cell types which secrete protons with fluorescent and optical microscopy; and (4) determine the mechanism of regulation of transepithelial transport using all the above techniques. These studies will supply insights into the pathway which mediates proton secretion in the terminal portion of the nephron and will provide a better understanding of the role of the IMCD in renal acid-base balance. During my postdoctoral training at the NIH with Dr. Maurice Burg, I learned the techniques of in vitro microperfusion and fluorescence microscopy, and I used these to examine the mechanisms of HCO3 and ammonia transport in the proximal tubule and collecting duct segments. These techniques have been successfully transferred to my new laboratory at Southwestern Medical School. I will now apply these techniques (along with a more sensitive assay for total CO2 which I developed specially for these studies), to address the above problems in the rat inner medullary collecting duct. My sponsor, Dr. Robert Alpern, has extensive experience performing similar studies in the proximal tubule and will be involved extensively in the supervision of these studies. In addition, Dr. Donald Seldin, who has a longstanding interest in distal acidification, will also be involved.