Regulation of renal Na handling in the collecting duct by local purinergic tone

局部嘌呤能调节肾集合管中钠的处理

• 批准号: 7932682
• 负责人: James D Stockand
• 金额: $ 37.13万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7932682
• 关键词: Address; Affect; Aldosterone; Americas; Animals; Blood Pressure; Cells; Complement; Connexins; Cues; Diet; Distal; Diuresis; Down-Regulation; Duct (organ) structure; Electrophysiology (science); Employee Strikes; Engineering; Environment; Equilibrium; Event; Excretory function; Feedback; Financial compensation; Healthcare; Hereditary Disease; Homeostasis; Human; Hypertension; Hypotension; Immunofluorescence Immunologic; Immunohistochemistry; Kidney; Knock-out; Link; Locales; Location; Measurement; Measures; Mediating; Mineralocorticoids; Molecular; Molecular Genetics; Molecular Mechanisms of Action; Mono-S; Mus; Mutagenesis; Natriuresis; Nephrons; P2Y2 receptor; Physiological; Plasma; Play; Quality of life; Regimen; Regulation; Relative (related person); Renin; Renin-Angiotensin-Aldosterone System; Role; Signal Pathway; Signal Transduction; Sodium; Sodium Chloride; Source; Stimulus; System; Test Result; Testing; Tissues; Urine; Water; autocrine; blood pressure regulation; epithelial Na+ channel; feeding; gain of function; paracrine; pressure; public health relevance; reconstitution; response; salt sensitive; tissue fixing; urinary

DESCRIPTION (provided by applicant): The activity of the epithelial Na+ channel (ENaC) in principal cells of the aldosterone-sensitive distal nephron is central to renal salt and water handling, and thus, regulation of blood pressure. Indeed, gain and loss of ENaC function causes marked increases and decreases in blood pressure. Negative-feedback regulation of ENaC by the renin-angiotensin-aldosterone system (RAAS) is well described where changes in blood pressure ultimately affect ENaC activity in the kidney. Emerging evidence suggests that ENaC is also under feedback control by signaling intrinsic to the kidney mediated by local factors. However, compared to extrinsic regulation by RAAS, less is known about intrinsic control. Purinergic signaling factors are leading candidates as autocrine/paracrine factors important to distal nephron Na+ transport. Our overarching idea is that distal nephron salt and water handling is influenced by intrinsic systems to lessen distal compensation of proximal events enabling excretion to appropriately match systemic conditions. Loss of such intrinsic regulation is expected to cause or exacerbate improper renal Na+ retention and thus, hypertension. It is striking that mice engineered to lack purinergic P2Y2 receptors or connexin 30 hemi-channels, which likely are responsible, in part, for ATP release in the distal nephron, have hypertension associated with facilitated renal Na+ retention. In consideration of our strong preliminary results, we test our central hypothesis that physiological down- regulation of ENaC activity in response to local ATP signaling in the distal nephron through luminal P2Y2 receptors tempers Na+ reabsorption by addressing four specific aims: 1) determine whether physiological concentrations of ATP affect ENaC activity in the mammalian distal nephron and determine the cellular signaling pathway and mechanism of action; 2) determine the consequence of dysfunctional regulation of ENaC by compromised paracrine/autocrine ATP signaling; 3) define the role of connexin 30 in ATP regulation of ENaC; and 4) quantify the relation between systemic salt-loading and regulation of ENaC activity in the distal nephron by purinergic tone. We investigate purinergic regulation of ENaC using a comprehensive strategy combining direct measurements of channel activity with electrophysiology with a molecular genetics approach that unequivocally establishes the role of the P2Y2 receptor and probes Cx30 as a conduit for autocrine ATP release. Physiologically relevant tissue (freshly isolated murine collecting duct) containing native ENaC in its normal cellular environment is used. Moreover, the scope of this proposal is comprehensive probing regulation of ENaC by purinergic tone and ATP release via Cx30 in the collecting duct from the animal to molecular mechanism of action. PUBLIC HEALTH RELEVANCE: Hypertension is prevalent in America and continues to rise making it one of the major obstacles for better quality of life and health care in the U.S. A. Appropriate salt handling by the kidneys is critical to proper control of blood pressure. The current proposal investigates the cellular and molecular mechanisms underlying renal salt handling particularly at the distal nephron, the location where systemic salt and water balance is fine-tuned in humans.

描述（由申请人提供）：上皮Na+通道（ENAC）在醛固酮敏感的远端肾单位的主要细胞中的活性对于肾脏盐和水的处理至关重要，因此是血压的调节。实际上，ENAC功能的增益和丧失会导致血压明显增加和降低。肾素 - 血管紧张素 - 醛固酮系统（RAAS）对ENAC进行负反馈调节，在血压变化最终会影响肾脏的ENAC活性的情况下得到很好的描述。新兴的证据表明，ENAC也通过向局部因素介导的肾脏发出固有的信号来控制反馈。但是，与RAAS外部调节相比，对内在对照的了解较少。嘌呤能信号传导因子是主要候选者，因为自分泌/旁分泌因子对远端NA+转运很重要。我们的总体想法是，远端肾脏盐和水的处理受到内在系统的影响，以减少近端事件的远端补偿，从而使排泄以适当匹配全身条件。这种内在调节的丧失有望导致或加剧不当的肾脏NA+保留率，因此会导致高血压。令人震惊的是，缺乏嘌呤能P2Y2受体或连接蛋白30半通道的小鼠可能部分造成了与远端肾脏中的ATP释放有关的，它具有与促进的肾脏Na+保留相关的高血压。考虑到我们的强烈初步结果，我们检验了我们的中心假设，即通过腔内肾脏中的局部ATP信号对ENAC活性的响应，通过腔内P2Y2受体在远端NEPHRON中响应局部ATP信号转化，通过解决四个特定目的来吸收Na+ Na+通过四个特定目的：1）确定ATP远处远处的eNaC活性和哺乳动物的机制，并确定哺乳动物的机制和细胞的机制。 2）通过受损的旁分泌/自分泌ATP信号传导对ENAC的功能失调调节的结果； 3）定义连接蛋白30在ENAC的ATP调节中的作用； 4）通过嘌呤能音调量化全身盐加载与ENAC活性调节之间的关系。我们使用综合策略对ENAC进行了嘌呤能调节，该策略将通道活性与电生理学的直接测量与分子遗传学方法结合在一起，该方法明确地确立了P2Y2受体的作用，并将CX30作为自动分泌ATP释放的渠道。使用了在正常细胞环境中包含天然ENAC的生理相关组织（新鲜分离的鼠收集管）。此外，该提案的范围是通过嘌呤能音调对ENAC的全面调节，并通过CX30释放ATP在从动物到分子作用机理的收集导管中释放。 公共卫生相关性：高血压在美国普遍存在，并继续上升，使其成为美国更好的生活质量和医疗保健的主要障碍之一A.肾脏适当的盐处理对于适当控制血压至关重要。当前的建议研究了肾脏盐处理的基础细胞和分子机制，尤其是在远端的肾脏盐，该位置是人类进行了全身盐和水平衡的位置。