ACID-BASE TRANSPORT IN INNER MEDULLARY COLLECTING DUCTS

这项建议旨在研究分配、机制和 大鼠延髓内侧H/HCO3转运的调节 集合管(IMCD)。此前的研究已经证实， IMCD是尿酸和净酸的主要部位 分泌物。最近的形态和功能研究表明 广泛研究了H/HCO3的作用机制和调节 在皮质和外髓集合管中的运输。这个 IMCD的体外微灌流研究尚未见报道 因为它的技术难度。由于最近的一些 随着技术的进步，现在可以从 无菌动物。 我们将在体外分离和灌流IMCD，使我们能够(1) 确定H/HCO3输运的轴向分布 (2)利用荧光识别转运机制 细胞pH值的测量；(3)确定分泌的细胞类型 质子的荧光和光学显微镜；和(4)确定 ALL调节跨上皮转运的机制 以上技巧。这些研究将为我们提供对 在末端调节质子分泌的途径 肾单位和将提供一个更好的理解的作用 肾脏酸碱平衡中的IMCD。 在我和莫里斯·伯格博士一起在美国国立卫生研究院进行博士后培训期间， 我学到了体外微灌技术和 荧光显微镜，我用这些来检查机制 HCO3和氨在近端小管和集合处的转运 风管管段。这些技术已经成功地转移到 送到我在西南医学院的新实验室。我现在就会 应用这些技术(以及更灵敏的总 我专门为这些研究开发的二氧化碳)，以解决 大鼠内髓集合管存在上述问题。 我的赞助人罗伯特·阿尔珀恩博士有丰富的表演经验 近端小管的类似研究，并将参与 广泛参与对这些研究的监督。此外，Dr。 唐纳德·塞尔丁，他长期对远端有兴趣 酸化，也会涉及到。

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.