Microvascular Transport in the Renal Medulla

肾髓质中的微血管运输

• 批准号: 7987443
• 负责人: THOMAS L PALLONE
• 金额: $ 5.65万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-15 至 2010-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7987443
• 关键词: Acetylcholine; Acids; Albumins; Bathing; Blood flow; Bradykinin; Cells; Chemicals; Communication; Confocal Microscopy; Connexins; Cyclic AMP; Cytoplasm; Deposition; Diffusion; Dilator; Docking; Electric Capacitance; Electrophysiology (science); Endothelial Cells; Endothelium; Excision; Fluo 4; Fluorescein-5-isothiocyanate; Fluorescence; Fluorescent Probes; Gap Junctions; Generations; Giant Cells; Heptanol; Herbimycin; Image; Image Analysis; In Vitro; Injection of therapeutic agent; Injury; Instruction; Ion Channel; Ions; Lasers; Letters; Measures; Mediating; Membrane Potentials; Methods; Modeling; NG-Nitroarginine Methyl Ester; Nephrons; Oxygen measurement, partial pressure, arterial; Peptides; Perfusion; Pericytes; Permeability; Phenylephrine; Physiologic pulse; Physiological Processes; Play; Principal Investigator; Protein Isoforms; Rectum; Regulation; Research Personnel; Resistance; Role; Rupture; Series; Signal Transduction; Signaling Molecule; Smooth Muscle; Sodium Chloride; Source; Study Subject; System; Testing; Urea; Urine; Variant; Vasodilation; Vasodilator Agents; Video Microscopy; Water; base; cell type; extracellular; fluorescein isothiocyanate dextran; inhibitor/antagonist; inward rectifier potassium channel; kidney medulla; lucifer yellow; migration; patch clamp; prevent; programs; response; solute; src-Family Kinases; wortmannin

Program Director/Principal Investigator (Last, First, Middle): Pallone, Thomas L. PROJECT SUMMARY (See instructions): The vasa recta of the renal medulla trap NaCI and urea deposited to the interstitium by nephrons and distribute blood flow to the outer and inner medulla. Descending vasa recta (DVR) supply all blood flow to both regions. The cells that comprise the DVR wall (smooth muscle / pericytes and endothelia) regulate vasoactivity through the interactions of ion channels and signaling molecules. DVR endothelia provides both barrier (permeability) function and regulates vasoactivity. The endothelium is "mechanosensitive" such that increases in luminal flow yield increases in cytoplasmic Ca2+ ([Ca2+]cYr), NO generation and transmural solute permeability. Electrophysiological studies of the DVR endothelium have shown that it is an electrical syncytium in which cells strongly couple to one another via gap junctions. External K+ is a strong regulator gap junction conductance. Strong inward rectifier K+ channel isoforms regulate membrane potential and induce hyperpolarization in response to small elevations of external K+ ion concentration. Thus K+ ion may play a key role in the regulation of perfusion of the renal medulla. We propose to study the function of the DVR endothelium with three Aims. In Aim 1, hydraulic permeability, vasoactivity, NO generation and [Ca2+]cvT will be quantified as a function of external K+ concentration. The separate roles of K(R and BKca channels to mediate the endothelium dependent relaxing functions and modulation of permeability will be tested. The role of BKCa channels as a putative source of K+ ion will be examined by activating them and blocking their effects with K|R channel inhibition. In Aim 2, the ability of gap junctions to communicate between endothelia and pericytes will be studied. The spread of current and fluorescent probes between cells will be quantified with electrophysiology and fluorescent imaging. The ability of gap junction blockade with K+ ion, specific peptide and nonspecific chemical inhibitors to prevent conduction of current and fluorescent probe diffusion will be tested. Finally, the ability of gap junctions to conduct both vasodilator and constrictor responses along the DVR axis will be quantified by microvessel perfusion, videomicroscopy and image analysis. In Aim 3 the mechanosensitivity of DVR endothelium will be explored. The requisite roles for [Ca2+]Cvr elevation and signaling via PI3kinase to facilitate NO generation will be tested. In separate series, effects of Ca2+ entry into the endothelium and signaling via PISkinase to mediate flow dependent increases in permeability will be explored. Independence of permeability modulation from NO will be explored for PI3kinase during NOS blockade. RELEVANCE (See instructions): Descending vasa recta provide all blood flow to the medulla of the kidney, a region vital to regulation of the elimination of salt and water in the urine. The medulla has very low oxygen tension and is vulnerable to injury when blood flow to it decreases. Regulation of contraction and dilation of descending vasa recta is a vital physiological process and is the subject of study in this proposal. PROJECT/

项目总监/首席研究员（最后，第一，中间）：Pallone，Thomas L. 项目摘要（请参阅说明）： 肾脏陷阱Naci和尿素的Vasa Recta被肾单键和尿素沉积在间质中 将血流分配到外部和内部髓质。下降的Vasa Recta（DVR）向所有血流提供 两个地区。包括DVR壁（平滑肌 /周细胞和内皮）的细胞调节 通过离子通道和信号分子的相互作用的血管活性。 DVR Endothelia提供两者 屏障（渗透率）功能并调节血管活性。内皮是“机械敏感的”，这样 细胞质Ca2+（[Ca2+] Cyr）中腔流量的增加，没有产生和透射 溶质渗透性。 DVR内皮的电生理研究表明它是一种电气生理研究 合成细胞通过间隙连接强烈彼此彼此对彼此进行。外部K+是强大的调节器 间隙连接电导。强内整流器K+通道同工型调节膜电位，并且 响应外部K+离子浓度的较小升高而诱导超极化。因此K+离子可以 在调节肾脏髓质的调节中起关键作用。 我们建议以三个目标研究DVR内皮的功能。在AIM 1中，液压 渗透性，血管活性，没有产生和[Ca2+] CVT将被量化为外部K+的函数 专注。 K（R和BKCA通道介导依赖内皮的放松的单独角色 将测试渗透率的功能和调节。 BKCA渠道作为K+的推定来源的作用 离子将通过激活它们并通过k | r通道抑制阻止其效果来检查离子。在AIM 2中 将研究间隙连接在内皮和周细胞之间进行交流的能力。传播 细胞之间的电流和荧光探针将用电生理和荧光定量 成像。 GAP连接用K+离子，特异性肽和非特异性化学抑制剂的能力 为了防止传导电流和荧光探针扩散。最后，差距的能力 沿DVR轴进行血管扩张器和收缩响应的连接将通过 微血管灌注，视频显微镜和图像分析。在AIM 3中DVR的机械敏感性 将探索内皮。 [Ca2+] CVR高程和通过PI3Kinase发出信号的必要角色 促进不会测试任何一代。在单独的系列中，CA2+进入内皮的影响和 通过piskinase信号传导将探索渗透率的介导依赖性依赖性。独立 在非NOS封锁期间，将探讨NO的渗透性调制。 相关性（请参阅说明）： 下降的Vasa Recta为肾脏的髓质提供了所有血液，这对于调节的区域至关重要 消除尿液中的盐和水。髓质的氧气张力非常低，很容易受到影响 当血液流动减少时受伤。调节收缩和降量河直肠的扩张是一个 重要的生理过程，是该提案中的研究主题。 项目/