Role of the kidneys in hypertension: paracrine actions of NO in the renal medulla

肾脏在高血压中的作用：肾髓质中 NO 的旁分泌作用

• 批准号: 7808018
• 负责人: Maria Marcela Herrera
• 金额: $ 5.22万
• 依托单位: HENRY FORD HEALTH SYSTEM
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7808018
• 关键词: AQP1 gene; Blood; Blood Pressure; Blood Vessels; Blood flow; Cell membrane; Chest; Confocal Microscopy; Data; Defect; Development; Diffusion; Electrodes; Endothelium; Fluorescent Dyes; Gene Transfer; Hypertension; Kidney; Knockout Mice; Left; Measures; Mus; Nephrons; Nitric Oxide; Pericytes; Play; Population; Production; Rectum; Regulation; Relaxation; Renal Blood Flow; Role; Structure of ascending limb of Henle' s loop; Technology; Thick; Thoracic aorta; Time; Tubular formation; Water; basolateral membrane; blood pressure regulation; extracellular; hypertension treatment; kidney medulla; paracrine; tool

DESCRIPTION (provided by applicant): Hypertension afflicts approximately 1/3 of the U.S. population. The kidney plays an important role in the regulation of blood pressure through the regulation of extracellular volume. Renal nitric oxide (NO) plays an important role in the regulation of extracellular volume and thus blood pressure. Inhibition of renal NO production in general and in the renal medulla specifically causes hypertension. The latter is due to changes in medullary blood flow and nephron transport. In the renal medulla, NO dilates the vasa recta pericytes to increase medullary blood flow. At least some of this NO comes from the adjacent thick ascending limb of the loop of Henle (THAL). Free diffusion is assumed to be the primary mechanism whereby NO leaves the THAL and enters the pericyte. However we have recently shown that aquaporin-1 (AQP-1) transports NO across cell membranes 4 times faster than free diffusion and that AQP-1-dependent NO transport is required for endothelium-induced relaxation of thoracic aortas. Although THALs reabsorb no water, their basolateral membranes are water permeable. Our preliminary data show that this is in part due to AQP-1, which is also expressed in the vasa recta. We hypothesize that AQP-1 transports NO out of the THAL and into the vasa recta pericytes. First, we will investigate whether AQP-1 transports NO out of the THAL by measuring NO efflux from single, microperfused THALs isolated from wild-type and AQP-1 knockout (-/-) mice using a NO-selective electrode. Second, we will investigate whether AQP-1 transports NO into vasa recta pericytes by measuring NO influx into single, microperfused vasa recta isolated from wild-type and AQP-1 -/- mice using fluorescent dye and fluorescent confocal microscopy. Third, we will investigate whether AQP-1-dependent NO transport is involved in tubular vascular crosstalk between the THAL and vasa recta pericytes by measuring the effect of stimulating NO production by the THAL on NO influx into descending vasa recta from wild-type and AQP-1 -/- mice using a single, isolated THAL with an adjacent descending vasa recta attached. Finally, we will measure the effect of restoring AQP-1 expression by gene transfer technology specifically in the THAL, vasa recta pericytes, or both on: 1. Efflux of NO out of the THAL, 2. Influx of NO into the Vasa recta and 3) THAL-derived NO-dependent relaxation of vasa recta. Data from this proposal will contribute to our understanding of regulation of renal blood flow. Defects in AQP-1 - dependent NO transport from the THAL to the DVR may play a role in the development of hypertension. Results from this proposal may offer new targets for the development of pharmacological tools for the treatment of hypertension.

描述（由申请人提供）：大约 1/3 的美国人口患有高血压。肾脏通过调节细胞外容量在血压调节中发挥重要作用。肾一氧化氮 (NO) 在调节细胞外容量和血压方面发挥着重要作用。抑制肾整体和肾髓质中 NO 的产生会导致高血压。后者是由于髓质血流和肾单位运输的变化所致。在肾髓质中，NO 扩张直肠血管周细胞以增加髓质血流量。至少有一些 NO 来自邻近的亨利袢 (THAL) 粗升肢。自由扩散被认为是 NO 离开 THAL 并进入周细胞的主要机制。然而，我们最近发现水通道蛋白-1 (AQP-1) 跨细胞膜转运 NO 的速度比自由扩散快 4 倍，并且内皮诱导的胸主动脉舒张需要依赖 AQP-1 的 NO 转运。尽管 THAL 不重吸收水，但它们的基底外侧膜是透水的。我们的初步数据表明，这部分是由于 AQP-1，它也在直肠血管中表达。我们假设 AQP-1 将 NO 从 THAL 转运到直肠血管周细胞中。首先，我们将通过使用 NO 选择性电极测量从野生型和 AQP-1 敲除 (-/-) 小鼠分离的单个微灌注 THAL 的 NO 流出来研究 AQP-1 是否将 NO 转运出 THAL。其次，我们将通过使用荧光染料和荧光共聚焦显微镜测量从野生型和 AQP-1 -/- 小鼠分离的单个微灌注直肠血管的 NO 流入，来研究 AQP-1 是否将 NO 转运到直血管周细胞中。第三，我们将通过测量 THAL 刺激 NO 产生对野生型和 AQP-1 -/- 小鼠 NO 流入降直血管的影响，研究 AQP-1 依赖性 NO 转运是否参与 THAL 和直肠周细胞之间的管状血管串扰，使用单个分离的 THAL 并附有相邻的直降血管。最后，我们将测量通过基因转移技术恢复 AQP-1 表达的效果，特别是在 THAL、直肠血管周细胞或两者中：1. NO 流出 THAL，2. NO 流入直肠血管，3) THAL 衍生的 NO 依赖性直肠血管松弛。该提案的数据将有助于我们了解肾血流的调节。 AQP-1 依赖性 NO 从 THAL 到 DVR 的转运缺陷可能在高血压的发生中发挥作用。该提案的结果可能为开发治疗高血压的药理学工具提供新的目标。