Epithelial Na Channels and Regulation of Na Excretion

上皮钠通道和钠排泄的调节

• 批准号: 7903717
• 负责人: LAWRENCE G PALMER
• 金额: $ 1.7万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-21 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7903717
• 关键词: Acute; Adrenal Glands; Aldosterone; Animals; Antibodies; Apical; Behavior; Cell surface; Chronic; Cleaved cell; Cyclic AMP; Defect; Diet; Electrophysiology (science); Enzymes; Event; Excretory function; Feedback; Gene Proteins; Genes; Glucocorticoids; Homebound Persons; Hormonal; Hormones; Hour; Hypertension; Immunoblotting; In Vitro; Infusion procedures; Kidney; Lead; Measures; Molecular; Mus; Oocytes; Pathway interactions; Phosphotransferases; Probability; Process; Protein-Serine-Threonine Kinases; Proteins; Rattus; Regulation; Research; Retrieval; Role; Serum; Sodium; Sodium Chloride; Steroids; Surface; System; Techniques; Testing; Work; abstracting; epithelial Na+ channel; glycosylation; in vivo; protein expression; response

DESCRIPTION (provided by applicant): ABSTRACT Epithelial Na channels control the reabsorption of salt by the kidney. They are essential for adapting to different levels of sodium in the diet, and defects in their regulation can lead to hypertension. Aldosterone is the major hormonal factor influencing these channels, but the mechanisms by which regulation is exerted are not fully understood. We will test the hypothesis that changes in processing and distribution of channel protein is a major factor underlying this regulation. We will use a combination of electrophysiological techniques and immunoblotting using antibodies specific for the 3 channel subunits alpha, beta and gamma ENaC to examine changes in the total amount of protein, in the processing of protein by proteolytic and glycosylating enzymes, and the expression of protein at the cell surface, and to correlate these events with channel activity in rats during salt restriction and challenge with aldosterone. We will compare these effects on the channels with those of other Na transporters including NaCl and NaK2Cl cotransporters and the Na/H exchanger. We will then examine the behavior of these proteins during acute salt repletion, where large changes in Na excretion can occur in a few hours. In this scenario we will also examine the role of reduction in channel open probability in reducing Na reabsorption and facilitating Na excretion. We will alos examine the molecular mechanisms underlying the effects of Na on open probability using the Xenous oocyte expression system. Finally we will test the hypothesis that the serine/threonine kinase SGK is a key protein for control of channel activity by assessing the activation of channels in mice lacking the gene for this kinase. We will measure channel activity as well as channel protein in animals in which hormone levels are changed over a few hours (with hormone infusion), over a few days (short-term salt restriction) or over a week or more (long-term salt restriction, long-term hormone infusion). The results will further our understanding of how these channels are regulated in vivo. NARRATIVE Disregulation of epithelial Na channels underlies most forms of monogenic hypertension. Yet how channels are normally controlled by adrenal steroids and other hormones remains poorly understood. The work described in this proposal will elucidate how these control mechanisms work and will enhance our understanding of how hypertension develops and impact how it is treated.

描述（由申请人提供）： 抽象的 上皮钠通道控制肾脏对盐的重吸收。它们对于适应饮食中不同钠含量至关重要，其调节缺陷可能导致高血压。醛固酮是影响这些通道的主要激素因素，但其调节机制尚不完全清楚。我们将检验以下假设：通道蛋白的加工和分布的变化是这种调节的主要因素。我们将结合使用电生理学技术和免疫印迹技术，使用针对 3 个通道亚基 α、β 和 γ ENaC 的特异性抗体来检查蛋白质总量、蛋白水解酶和糖基化酶对蛋白质的加工以及蛋白质表达的变化。在细胞表面，并将这些事件与大鼠在限盐和醛固酮激发期间的通道活性相关联。我们将比较这些对通道的影响与其他 Na 转运蛋白（包括 NaCl 和 NaK2Cl 协同转运蛋白以及 Na/H 交换器）的影响。然后，我们将检查这些蛋白质在急性盐补充过程中的行为，其中钠排泄可能在几个小时内发生巨大变化。在这种情况下，我们还将研究通道开放概率的减少在减少 Na 重吸收和促进 Na 排泄方面的作用。我们还将使用异种卵母细胞表达系统检查 Na 对开放概率影响的分子机制。最后，我们将通过评估缺乏丝氨酸/苏氨酸激酶 SGK 基因的小鼠中通道的激活情况来检验丝氨酸/苏氨酸激酶 SGK 是控制通道活性的关键蛋白的假设。我们将测量激素水平在几个小时（激素输注）、几天（短期限盐）或一周或更长时间（长期盐）内发生变化的动物的通道活性和通道蛋白。限制、长期激素输注）。这些结果将进一步加深我们对这些通道在体内如何调节的理解。 叙述 上皮钠通道失调是大多数单基因高血压的基础。然而，肾上腺类固醇和其他激素通常如何控制通道仍然知之甚少。该提案中描述的工作将阐明这些控制机制如何发挥作用，并将增强我们对高血压如何发展及其治疗方式的影响的理解。