Two-Pore Domain Potassium Channels and Aldosterone Secretion

双孔域钾通道和醛固酮分泌

• 批准号: 7599669
• 负责人: PAULA Q BARRETT
• 金额: $ 40.12万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-03 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7599669
• 关键词: Acids; Adrenal Glands; Aldosterone; Aldosterone Receptors; Angiotensin II; Animal Experimentation; Bathing; Calcium; Cardiovascular system; Cells; Cellular biology; Chronic Kidney Failure; Data; Diet; Disease; Disease Progression; Electrophysiology (science); Equilibrium; Excretory function; Family; Financial compensation; Generations; Genetic; Heart failure; Homeostasis; Hormonal; Hypertension; Immunohistochemistry; In Situ Hybridization; Infusion procedures; Kidney; Knock-out; Knockout Mice; Mediating; Membrane; Membrane Potentials; Membrane Proteins; Metabolic; Mineralocorticoid Receptor; Molecular; Mus; Patients; Physiological; Potassium; Potassium Channel; Primary Hyperaldosteronism; Production; Property; Pump; Regulation; Renin; Research; Resistance; Rest; Role; Serum; Slice; Sodium Chloride; Stimulus; System; T-Type Calcium Channels; Testing; Tissues; Water; Work; Zona Glomerulosa; congenic; deprivation; early onset; extracellular; in vitro testing; in vivo; mature animal; mouse model; novel; patch clamp; receptor; response; salt balance; steroid hormone; therapeutic target; tool; urinary; voltage

DESCRIPTION (provided by applicant): Aldosterone is an early-onset pathogenic stimulus that adversely influences cardiovascular and renal homeostasis. It is elevated in heart failure, chronic kidney disease and some forms of hypertension. Although the production of aldosterone in vivo has long been known to be regulated by Ang I and potassium, the contribution of K channel regulation to the physiological actions of Ang II, though hypothesized, has remained unproven. The recent generation of TASK-1, TASK-3, and TASK-1/TASK-3 knockout mice offers the exciting possibility to establish the functional importance of TASK channel regulation to the physiological control of aldosterone production in vivo. Our hypothesis that TASK subunits contribute to background K currents and the control of membrane potential by Ang II and acidification in the aldosterone secreting adrenal zona glomerulosa (ZG) cells is tested in vitro. Moreover, the hypothesis that these channels are important in the regulation of aldosterone production and salt/water balance in vivo is determined under basal conditions and during hormonal and metabolic challenge (i.e., AngII infusion, Na loading and deprivation). We pursue the following specific aims: Aim 1: Generate and validate novel conventional and conditional TASK channel subunit knockout mouse lines using qRT-PCR, in situ hybridization, and immunohistochemistry; Aim 2: Determine membrane properties of ZG cells in control and TASK channel knockout mice, characterizing background K channel currents and their modulation by AngII, extracellular K and bath pH, and evaluating the role of these channels in setting membrane voltage and supporting ZG cell excitability; Aim 3: Evaluate the importance of TASK channel expression to the control of aldosterone production in vivo in control and TASK channel knockout mice determining: the steady-state aldosterone secretory response to RAAS suppression caused by dietary manipulation of salt balance, and the aldosterone secretory response to the delivery of exogenous AngII or acid loading in vivo. The strength of this proposal lies in the combined use of molecular and cell biology, electrophysiology and whole animal experimentation. Minimally, our efforts will clarify the role of TASK channels in the production of aldosterone. Optimally, our work will identify a new target for the therapy of patients with heart failure, chronic kidney disease and resistant hypertension. Project Narrative: Idiopathic primary hyperaldosteronism (IHA) is present in 13% of non-selected hypertensive patients and rises to 20% among those that have resistant hypertension. Using a combination of cellular and in vivo approaches our studies identify TASK K channels as critical membrane proteins that control the production of aldosterone, the steroid hormone that is elevated in IHA. The identification of this target can be used to generate a useful therapy for patients with IHA but also for patients with heart failure and chronic kidney disease where elevated aldosterone also hastens disease progression.

描述（由申请人提供）：醛固酮是一种早发性致病刺激物，会对心血管和肾脏稳态产生不利影响。它在心力衰竭、慢性肾病和某些形式的高血压中升高。尽管长期以来已知体内醛固酮的产生受到 Ang I 和钾的调节，但 K 通道调节对 Ang II 生理作用的贡献虽然是假设的，但仍未得到证实。最新一代的 TASK-1、TASK-3 和 TASK-1/TASK-3 敲除小鼠为确定 TASK 通道调节对体内醛固酮产生的生理控制的功能重要性提供了令人兴奋的可能性。我们的假设是，TASK 亚基有助于背景 K 电流，并通过 Ang II 控制膜电位，并在分泌醛固酮的肾上腺球带 (ZG) 细胞中进行酸化，并在体外进行了测试。此外，这些通道对于调节体内醛固酮产生和盐/水平衡很重要的假设是在基础条件下以及在激素和代谢挑战期间（即AngII输注、Na负荷和剥夺）确定的。我们追求以下具体目标： 目标 1：使用 qRT-PCR、原位杂交和免疫组织化学生成并验证新型常规和条件 TASK 通道亚基敲除小鼠系；目标 2：确定对照和 TASK 通道敲除小鼠中 ZG 细胞的膜特性，表征背景 K 通道电流及其受 AngII、细胞外 K 和浴 pH 的调节，并评估这些通道在设置膜电压和支持 ZG 细胞兴奋性方面的作用；目标 3：评估 TASK 通道表达对对照和 TASK 通道敲除小鼠体内醛固酮产生控制的重要性，确定：饮食控制盐平衡引起的 RAAS 抑制的稳态醛固酮分泌反应，以及体内外源 AngII 或酸负荷递送的醛固酮分泌反应。该提案的优势在于分子和细胞生物学、电生理学和整体动物实验的结合使用。至少，我们的努力将阐明 TASK 通道在醛固酮生成中的作用。最理想的情况是，我们的工作将为心力衰竭、慢性肾病和难治性高血压患者的治疗找到一个新的靶点。 项目叙述：特发性原发性醛固酮增多症 (IHA) 存在于 13% 的非选择性高血压患者中，而在难治性高血压患者中这一比例上升至 20%。通过结合细胞和体内方法，我们的研究确定 TASK K 通道是控制醛固酮（IHA 中升高的类固醇激素）产生的关键膜蛋白。该靶标的识别可用于为 IHA 患者提供有用的治疗方法，也可用于心力衰竭和慢性肾病患者，这些患者的醛固酮升高也会加速疾病进展。