Bicarbonate Transport by the Maturing Renal Tubule

代谢性酸中毒是一种常见但可能危及生命的疾病，当过多的酸 在血液中积累。肾脏是主要负责控制胃酸水平的器官 血液中皮质集合管（cortical collecting duct，CCD）是肾小管的一个关键部分，其适应于肾组织的水平。 酸并将其排出体外。长期的目标是确定CCD的嵌入细胞 通过改变酸和碳酸氢盐的运输来适应酸碱紊乱。兔子CCD， 正常分泌碳酸氢盐，暴露于pH 6.8孵育3小时分泌酸。一种新的蛋白质hensin， 在适应性B-嵌入细胞（IC）周围的细胞外基质（ECM）中表达。目标1检查 环孢菌素A（CsA）如何通过阻止B-IC的适应而引起远端肾小管酸中毒。CSA 通过抑制亲环素的脯氨酸顺式/反式异构酶活性来抑制hensin聚合。 使用这些功能的特异性抑制剂的研究是在培养的IC和CCD中进行的， 6.8 x 3 h以模拟酸中毒。亲环蛋白的“敲低”将决定哪种亲环蛋白在细胞内是重要的。 在培养的IC中聚合hensin以及这种亲环素的缺陷是否导致酸中毒。目的2 检查了半乳糖凝集素-3在亨辛聚合中的作用。半乳糖凝集素-3在体外可帮助甘草素。这 aim将确定哪些细胞表达半乳糖凝集素-3以及在酸中毒期间是否存在刺激。目的 将确定半乳糖凝集素-3是否与适应CCD的ECM中的汉逊菌素结合，以及是否存在显性的 阴性galectin-3阻止hensin聚合和CCD中B-ICs的适应。这一目标将建立 表达的亲环素和半乳糖凝集素-3是否能协同参与汉逊菌素的体外聚合。目标3 决定了哪些整合素在IC中表达，哪些整合素与hensin相互作用。目标4审查了 hensin聚合在CCD IC适应代谢性代谢紊乱中的作用，假设代谢性代谢紊乱 通过降解亨辛并允许B-IC分泌碳酸氢盐来纠正亨辛聚合， 异常这些研究应该能显示汉逊菌素和相关蛋白质是如何介导肾脏的 适应酸碱失衡。

Metabolic acidosis is a common but potentially life-threatening disorder that occurs when too much acid accumulates in the blood. The kidney is the organ that is primarily concerned with controlling the level of acid in the blood. The cortical collecting duct (CCD) is a key segment of kidney tubule that adapts to the level of acid and pumps it out of the body. The long term goal is to determine how intercalated cells of the CCD adapt to acid-base disturbances by changing their transport of acid and bicarbonate. Rabbit CCDs, which normally secrete bicarbonate, exposed to 3h incubation at pH 6.8 secrete acid. The novel protein hensin is expressed in the extracellular matrix (ECM) surrounding adapting B-intercalated cells (ICs). Aim 1examines how Cyclosporin A (CsA) causes a distal renal tubular acidosis by preventing adaptation of B-ICs. CsA inhibits hensin pofymerization via an inhibition of the proline cis/trans isomerase activity of cyclophilin. Studies using specific inhibitors of these functions are performed in cultured ICs and CCDs incubated at pH 6.8 x 3 h to simulate acidosis. A "knockdown" of cyclophilin will determine which cyclophilin is important in polymerizing hensin in cultured ICs and whether a defect in this cyclophilin causes acidosis. Aim 2 examines the role of galectin-3 in hensin polymerization. Galectin-3 can help polymerize hensin in vitro. This aim will determine which cells express galectin-3 and whether there is stimulation during acidosis. The aim will determine if galectin-3 associates with hensin in the ECM in the adapting CCD and whether a dominant negative galectin-3 prevents hensin polymerization and adaptation of B-ICs in CCD. This aim will establish whether expressed cyclophilin and galectin-3 can cooperate in the in vitro polymerization of hensin. Aim 3 determines which integrins are expressed in ICs and which interact with hensin. Aim 4 examines the role of hensin polymerization in the adaptation of CCD ICs to metabolic alkalosis, with the hypothesis that alkalosis reduces hensin polymerization by degrading hensin and allowing B-ICs to secrete bicarbonate to correct the abnormality. These studies should show how hensin and associated proteins mediate the kidney's adaptation to acid-base disturbances.