REGULATION OF COLONIC H-K-ATPASE IN THE KIDNEY

描述(改编自申请人的摘要)：胃(G) 结肠(C)亚型H+/K+-ATPase(HKA)在低水平表达 在肾集合管(CD)细胞中，但这些HKA的功能作用(S) 仍然不确定。他们建议香港会计师公会特别扮演关键角色。 在肾脏中，HCO3-、K+和Na+在多种病理生理状态下转运。 我们的研究表明，在一定的条件下，cHKA的mrna和/或活性增加。 与增加的HCO3-递送到CD(近端RTA)或 钾耗竭(KD)。有趣的是，垂体切除术(HPX)抑制了 KD组cHKA表达增加，但近侧RTA表达无明显变化。他们 假设cHKA对酸碱、K+和Na+动态平衡至关重要： CHKA上调钝化HCO3-在增加交货量的情况下损失 HCO3-进入远端肾单位，加速KD大鼠对K+、Na+的重吸收。 为了阐明这一假设，我们建议检查分子和 CHKA在以下三个方面的功能调控：a)与增加 向远端小管输送HCO3-，但酸碱状态不同 平衡：乙酰唑胺(酸中毒)、氯离子耗竭(碱中毒)和 NaHCO3负荷(正常)；以及b)钾耗竭。酸碱和 电解质改变，离体灌流型CCD和OMCD中的HCO3-重吸收， 以及cHKA的皮质、髓质和肾单位节段的mRNA和蛋白 在大鼠和小鼠中被检测到(CHKA缺陷转基因和 野生型)伴有KD或向远端小管的HCO3递送增加。在KD大鼠中 实验将在HPX+激素替代中重复进行。最后，他们 将研究cHKA的转录调控。转cHKA基因小鼠 启动子-荧光素酶报告基因(PLR)的构建将在上面进行研究 模特们。再加上上述(A)和(B)项的数据，这些研究表明 在培养的肾脏细胞中进行研究的可能信号。这些将是 瞬时导入删除的LR构建体并在 测定启动子内敏感元件的体外条件 CHKA基因。对香港会计师公会监管的洞察将大大增强我们的 了解与电解液相关的各种病理情况 和酸碱异常。

DESCRIPTION (Adapted from the Applicant's Abstract): Both the gastric (g) and colonic (c) isoforms of H+/K+-ATPase (HKA) are expressed at low levels in renal collecting duct (CD) cells but the functional role(s) for these HKA remain uncertain. They propose that cHKA specifically plays a pivotal role in renal HCO3-, K+ and Na+ transport in several pathophysiologic states. Our studies show that cHKA mRNA and or activity is increased in conditions associated with increased HCO3- delivery to the CD (proximal RTA) or in potassium depletion (KD). Interestingly, hypophysectomy (HPX) suppresses increased expression of cHKA in KD but not in proximal RTA. They hypothesize that cHKA is vital to acid-base, K+ and Na+ homeostasis: Upregulation of cHKA blunts HCO3- loss in instances of increased delivery of HCO3- to the distal nephron and accelerates K+ and Na+ reabsorption in KD. To elucidate this hypothesis, we propose to examine the molecular and functional regulation of cHKA in: a) three models associated with increased delivery of HCO3- to the distal tubule but different states of acid-base balance: acetazolamide (acidosis), chloride depletion (alkalosis), and NaHCO3 loading (normal); and b) in potassium depletion. Acid-base and electrolyte changes, HCO3-reabsorption in isolated perfused CCD and OMCD, and cortical, medullary, and nephron-segment mRNA and protein for cHKA will be determined in rats and mice (both cHKA-deficient transgenic and wild-type) with KD or increased HCO3-delivery to distal tubules. In KD rats experiments will be repeated in HPX + hormonal replacement. Lastly, they will examine transcriptional regulation of cHKA. Mice transgenic for a cHKA promoter-luciferase reporter (PLR) construct will be studied in the above models. Coupled with the data from (a) and (b) above, these studies suggest possible signals for study in cultured renal cells. These will be transiently transfected with deleting constructs of LR and studied under in vitro conditions to determine the sensing elements within the promoter of cHKA cDNA. Insight into regulation of cHKA will significantly enhance our knowledge on a variety of pathologic conditions associated with electrolyte and acid-base abnormalities.