Epithelial Na Channels and Regulation of Na Excretion

上皮钠通道和钠排泄的调节

• 批准号: 7769927
• 负责人: LAWRENCE G PALMER
• 金额: $ 35.01万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7769927
• 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NA通道控制肾脏对盐的重吸收。它们对于在饮食中适应不同水平的钠水平至关重要，并且调节中的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子，但尚未完全了解调节的机制。我们将检验以下假设：通道蛋白的加工和分布变化是该调节的主要因素。我们将使用针对3通道亚基α，β和伽马ENAC特异性的电生理技术和免疫印迹的结合，以检查蛋白质总量的变化，以蛋白质水解和糖基化酶的表达来处理蛋白质的蛋白质。在细胞表面，并将这些事件与盐限制期间大鼠的通道活性相关联，并与醛固酮相关。我们将将这些对通道的影响与其他NA转运蛋白的影响进行比较，包括NaKl和NAK2CL共转运蛋白以及Na/H交换器。然后，我们将检查这些蛋白质在急性盐补充期间的行为，在几个小时内可能会发生大规模的Na排泄变化。在这种情况下，我们还将研究降低通道开放概率在减少NA重吸收和促进Na排泄的作用。我们将使用Xenous卵母细胞表达系统来检查Na对NA对开放概率的影响的分子机制。最后，我们将检验以下假设：丝氨酸/苏氨酸激酶SGK是通过评估缺乏该激酶基因的小鼠的通道激活来控制通道活性的关键蛋白。我们将测量动物中的通道活性以及通道蛋白，其中激素水平在几个小时内改变了激素水平（激素输注），几天（短期盐限制）或一周以上（长期盐）限制，长期激素输注）。结果将进一步了解这些渠道如何在体内调节。 叙述 上皮NA通道的疏离是大多数形式的单基质高血压的基础。然而，通常如何通过肾上腺类固醇和其他激素控制通道仍然知之甚少。本提案中描述的工作将阐明这些控制机制的工作原理，并将增强我们对高血压如何发展和影响其治疗方式的理解。