RENAL INTERCALATED CELL REGULATION AND DIFFERENTIATION

本研究项目的主要目标是调查 细胞和亚细胞机制负责肾脏调节 收集管的酸碱运输，并追踪 这种运输过程回到围产期。 拟议 研究将集中在两种类型的酸碱转运细胞 在集合管中，H+和HCO 3离子分泌 间充质（富含钙）细胞。 鉴定与功能 离体灌注兔集合管中单个细胞的测定 将使用最近开发的荧光染色技术进行， 包括那些探测线粒体、碳 凝集素的脱水酶活性、胞吞/胞吐作用和表面结合 并允许测量细胞pH值。将测量HCO 3净离子转运 通过微量热法。 为了确定 H ~+-ATP酶定位的两种类型的闰细胞 和Cl-HCO_3离子交换剂，鲁米那阴离子取代Cl-的效果 对HCO 3离子转运和细胞内pH的影响。 因为 髓质集合管H+分泌率高 (MCT)可能是由于相对酸性的骨髓 环境，调节HCO 3离子运输在这一段的反应 慢性全身性骨质疏松症将进行检查， 其中存在分泌H+和HCO 3离子的嵌入细胞的数量。 皮层收集区H ~+和HCO ~ 3离子分泌细胞的频率 肾小管（CCT），从遭受慢性干扰的动物中获得， 代谢和呼吸酸碱状态和循环 盐皮质激素水平将与HCO 3离子测量值进行比较 运输，以证实插入细胞可以被诱导的假设 来逆转它们的功能极性 发展功能 分化的闰细胞的特征（碳 脱水酶、细胞pH、内吞作用/胞吐作用、表面糖蛋白）将被 追溯到围产期和胚胎期，以建立一个 闰细胞的命运图。 作为调查的一部分， 确定细胞何时以及如何致力于分泌酸或 基础，存在或不存在之间的沟通， 主细胞将在未成熟的CCT中建立。 研究 在本申请中描述的应该让我们更好地理解如何 代谢和呼吸性酸碱紊乱，盐皮质激素 过量，遗传因素影响调节和发展， 闰细胞

The major objectives of this research project are to investigate the cellular and subcellular mechanisms responsible for the renal regulation of acid-base transport by the collecting duct and to trace the maturation of such transport processes back to the perinatal period. The proposed studies will focus on the two types of acid-base transporting cells identified in the collecting duct, the H+- and HCO3 ion-secreting intercalated (mitochondria-rich) cells. Identification and functional assay of individual cells in the isolated perfused rabbit collecting duct will be performed with recently developed fluorescence staining techniques, including those which probe for the presence of mitochondria, carbonic anhydrase activity, endocytosis/exocytosis and surface binding of lectins and permit measurement of cell pH. Net HCO3 ion transport will be measured by microcalorimetry. In order to identify the functional polarity of the two types of intercalated cells with respect to location of the H+-ATPase and Cl-HCO3 ion exchanger, the effect of luminal anion substitution for Cl- on HCO3 ion transport and intracellular pH will be studied. Because the high rate of H+ secretion characteristic of the medullary collecting tubule (MCT) may be due to conditioning by a relatively acidic medullary environment, regulation of HCO3 ion transport in this segment in response to chronic systemic alkalosis will be examined and the findings correlated with the numbers of H+- and HCO3 ion secreting intercalated cells present. The frequencies of H+- and HCO3 ion-secreting cells in cortical collecting tubules (CCT) obtained from animals subjected to chronic disturbances in metabolic and respiratory acid-base status and circulating mineralocorticoid levels will be compared with measurements of HCO3 ion transport to confirm the hypothesis that intercalated cells can be induced to reverse their functional polarity. The development of functional characteristics of the differentiated intercalated cell (carbonic anhydrase, cell pH, endocytosis/exocytosis, surface glycoproteins) will be traced back to the perinatal and embryonic periods in order to establish a fate map for the intercalated cell. As part of the investigation to determine when and how the cell becomes committed to secreting acid or base, the presence or absence of communication between intercalated and principal cells will be established in the immature CCT. The studies described in this application should allow us to better understand how metabolic and respiratory acid-base perturbations, mineralocorticoid excess, and genetic factors influence regulation and development of the intercalated cell.