Physiologic role of BK channel in distal nephron

BK通道在远端肾单位中的生理作用

• 批准号: 8107556
• 负责人: Donald E Kohan
• 金额: $ 19.23万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8107556
• 关键词: Acids; Address; Aldosterone; Amiloride; Animals; Antigens; Blood Pressure; Bowman' s space; Carrier Proteins; Cells; Data; Development; Diet; Disease; Distal; Duct (organ) structure; Electrolytes; Electrons; Epithelial Cells; Excretory function; Generations; Goals; Homeostasis; Hypertension; Individual; Intake; Intercalated Cell; KCNJ1 gene; Kidney; Knock-out; Liquid substance; Maintenance; Measurement; Measures; Mediating; Membrane; Metabolic; Methodology; Modeling; Monoclonal Antibodies; Mouse Strains; Mus; Na(+)-K(+)-Exchanging ATPase; Nephrons; Oryctolagus cuniculus; Ouabain; Pathway interactions; Perfusion; Physiological; Play; Potassium; Potassium Channel; Process; Pump; Rattus; Regulation; Relative (related person); Research Design; Retrieval; Role; Sodium; Staining method; Stains; Stretching; Sum; Techniques; Telemetry; Urine; Work; absorption; apical membrane; base; basolateral membrane; cell type; channel blockers; density; driving force; epithelial Na+ channel; feeding; iberiotoxin; in vivo; large-conductance calcium-activated potassium channels; mouse model; novel; public health relevance; uptake; urinary

DESCRIPTION (provided by applicant): Flow-stimulated K secretion in the distal nephron, including the connecting tubule (CNT) and cortical collecting duct (CCD), is mediated by a Ca2+ and stretch-activated BK channel located in the apical membrane; the BK channel is also critically involved in the renal adaptation to dietary K intake. The density of BK channels in acid-base transporting intercalated cells exceeds that in Na absorbing CNT/principal cells. However, functional measurements suggest that intercalated cells may not have a mechanism to load cells with K to sustain high rates of K secretion into the urinary fluid. The goal of this application is to determine whether BK channels in intercalated and/or principal cells mediate flow-stimulated net K secretion and thereby regulate total body K (and Na) homeostasis. To this end, we propose three Specific Aims (SAs): (1) to confirm, using a selective BK channel blocker, that flow-stimulated net K secretion in microperfused CDs isolated from WT and a mouse strain we will generate with floxed slo1, proposed to be used in SAs 2 and 3, is mediated by the BK channel; (2) to define the role of the 1 subunit of the BK channel in intercalated cells in the in vivo regulation of K secretion in the distal nephron by generating a mouse model with targeted deletion of the 1 subunit of the BK channel solely in intercalated cells within the distal nephron; and (3) to define the role of the 1 subunit of the BK channel in principal cells in the in vivo regulation of K secretion in the distal nephron by generating a mouse model with targeted deletion of the 1 subunit of the BK channel solely in principal cells within the distal nephron. To the extent that the magnitude of distal K secretion determines, in part, Na absorption, and animals with global deletion of BK channel subunits present with alterations in blood pressure, the impact of cell-specific deletion of the BK channel in the distal nephron on Na and K clearances and blood pressure (telemetry) will also be evaluated. The results of proposed studies will define the importance of BK channels in the regulation of renal K (and Na) excretion and maintenance of normal blood pressure, and promises to uncover mechanisms involved in the development and/or maintenance of hypertension and disorders of K excretion. PUBLIC HEALTH RELEVANCE: The proposed studies are designed to determine the physiologic role of BK potassium channels in the distal nephron of the kidney. The studies will define the importance of these channels in the regulation of kidney sodium and potassium excretion and maintenance of normal blood pressure. This work has the potential to uncover mechanisms involved in the development and/or maintenance of hypertension and disorders of potassium excretion.

描述（由申请人提供）：远端肾单位的流动刺激的K分泌，包括连接小管（CNT）和皮质收集管（CCD），由位于顶部膜中的Ca2+和拉伸激活的BK通道介导； BK通道还与饮食K摄入的肾脏适应有关。酸碱转运细胞中BK通道的密度超过了吸收CNT/主要细胞的Na。然而，功能测量表明，插入的细胞可能没有将K载入K含量高的k分泌速率加载到尿液中的机制。该应用的目的是确定插入和/或主要细胞中的BK通道是否介导流动刺激的净K分泌，从而调节总体K（和NA）稳态。为此，我们提出了三个特定目标（SAS）：（1）使用选择性的BK通道阻滞剂确认从WT中分离出的微填充CD中的流量刺激的净K分泌，我们将用Floxed Slo1生成的小鼠菌株，该菌株旨在用SAS 2和3用于SAS 2和BK通道介导。 （2）通过生成具有靶向缺失的小鼠模型，该模型的靶标缺失，BK通道在体内调节中的1个亚基在体内调节中，通过产生一个小鼠模型，该模型具有针对BK通道的1个亚基的靶向缺失，仅在远端肾小管中插入式细胞中的1个亚基； （3）通过生成具有靶向缺失的小鼠模型，该模型的靶向缺失仅在远端肾单位内的主细胞中，bk nephron的1个亚基在远端肾单位中定义了BK通道在主要细胞中的1个亚基的作用。在一定程度上，远端K分泌的大小部分决定了Na的吸收和具有血压变化的BK通道亚基的全球缺失，这是还将评估NAPHRON对Na和K清除率和血压（远程压力）的细胞特异性缺失的影响。拟议的研究结果将定义BK通道在调节肾脏K（和NA）排泄和正常血压的维持中的重要性，并有望揭示涉及K k排泄物的高血压和疾病的机制。 公共卫生相关性：拟议的研究旨在确定BK钾通道在肾脏远端的生理作用。研究将定义这些通道在调节肾脏钠和钾排泄的重要性以及正常血压的维持中的重要性。这项工作有可能发现参与高血压和/或维持钾外出疾病的机制。