Cellular Mechanisms for Tubuloglomerular Feedback

肾小球反馈的细胞机制

• 批准号: 7033818
• 负责人: Phillip Darwin Bell
• 金额: $ 7.06万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7033818
• 关键词: PC12 cells; adenosine; adenosine triphosphate; basolateral membrane; biological signal transduction; calcium flux; cell morphology; confocal scanning microscopy; fluorescence microscopy; hemodynamics; intracellular transport; kidney circulation; laboratory rabbit; membrane channels; mesangium; mitochondrial membrane; purinergic receptor; renal glomerulus; renal tubular transport; renal tubule; sodium chloride; voltage /patch clamp

DESCRIPTION (provided by applicant): Macula densa cells are located within the thick ascending limb; they detect changes in luminal fluid composition and transmit signals to the afferent arteriole, a process called tubuloglomerular feedback. Considerable effort has been directed towards elucidation of transport characteristics of these cells, in identifying the nature of mediator(s) that are released by macula densa cells and the signals that are sent to the underlying mesangial/afferent arteriolar complex. We have found that increases in luminal fluid sodium chloride concentration ([NaCI]L) activate a maxi anion channel leading to the movement of ATP across the basolateral membrane and direct, or with conversion to adenosine, afferent arteriole vasoconstriction and decreased GFR. This renewal is focused on an in depth analysis of this ATP signaling pathway. Studies will use the isolated perfused thick ascending limb-glomerular preparation and 2-photon microscopy, patch clamp, and molecular biology. Aim one is to elucidate the intracellular events that lead to the release of ATP across the basolateral membrane. We will test the hypothesis that macula densa cells exhibit unique properties of cytosolic calcium concentration [Ca2+], regulation and that [Ca2+]j plays a critical role in macula densa signaling. Studies will also define roles for macula densa cell volume and tubular flow in [Ca2+]j regulation and macula densa signaling. Aim two will test the hypothesis that increased macula densa [Ca2+]j results in mitochondrial Ca2+ uptake and enhanced ATP generation. Other work will define the intracellular events that activate the maxi anion channel and finally we will work towards defining the molecular identity of this ATP conductive pathway. Aim three will explore the role of ATP signaling to the mesangial/afferent arteriolar complex. Overall these studies should provide important new information regarding the role of ATP in macula densa signaling, activation of the tubuloglomerular feedback mechanism, and control of glomerular hemodynamics.

描述（由申请人提供）：致密斑细胞位于粗升肢内；它们检测管腔液体成分的变化并将信号传输到传入小动脉，这一过程称为肾小球反馈。为了阐明这些细胞的运输特性，鉴定致密斑细胞释放的介质的性质以及发送到下面的系膜/传入小动脉复合体的信号，人们付出了相当大的努力。我们发现，管腔液体氯化钠浓度（[NaCI]L）的增加激活最大阴离子通道，导致ATP穿过基底外侧膜移动并直接或转化为腺苷、传入小动脉血管收缩和GFR降低。此次更新的重点是对该 ATP 信号通路的深入分析。研究将使用分离灌注的厚升肢肾小球制剂和 2 光子显微镜、膜片钳和分子生物学。目标一是阐明导致 ATP 穿过基底外侧膜释放的细胞内事件。我们将检验以下假设：致密斑细胞表现出独特的胞浆钙浓度 [Ca2+] 调节特性，并且 [Ca2+]j 在致密斑信号传导中发挥关键作用。研究还将确定致密黄斑细胞体积和肾小管血流在 [Ca2+]j 调节和致密黄斑信号传导中的作用。目标二将检验以下假设：致密斑 [Ca2+]j 的增加会导致线粒体 Ca2+ 摄取和 ATP 生成增强。其他工作将定义激活 maxi 阴离子通道的细胞内事件，最后我们将致力于定义此 ATP 传导途径的分子身份。目标三将探讨 ATP 信号传导对系膜/传入小动脉复合体的作用。总的来说，这些研究应该提供关于 ATP 在致密斑信号传导、肾小球反馈机制激活和肾小球血流动力学控制中的作用的重要新信息。