20-HETE and EETs in pressure natriuresis

20-HETE 和 EET 在压力尿钠中的作用

• 批准号: 7367208
• 负责人: Richard J. Roman
• 金额: $ 30.25万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2008-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7367208
• 关键词: Acids; Acute; Address; Agonist; Antihypertensive Agents; Arachidonic Acids; Attenuated; Binding; Biological Assay; Blood Pressure; Blood Vessels; Blood flow; Chronic; Clinical; Collaborations; Cytochrome P450; Cytochromes; Development; Elevation; Enzyme Inhibitor Drugs; Enzyme Inhibitors; Enzymes; Experimental Genetics; Experimental Models; Fibrates; Henle' s loop; High Pressure Liquid Chromatography; Hydrostatic Pressure; Hydroxyeicosatetraenoic Acids; Hypertension; Infusion procedures; Intake; Intercellular Fluid; Kidney; Kidney Diseases; Laboratories; Measures; Mediating; Mediator of activation protein; Methods; Microdialysis; Modeling; Natriuresis; Nephrons; Oxidative Stress; Oxygen; Pathway interactions; Perfusion; Pharmacologic Substance; Play; Production; Proximal Kidney Tubules; Rat Strains; Rattus; Reactive Oxygen Species; Renal Blood Flow; Renal Hypertension; Renal function; Renal tubule structure; Research; Resistance; Role; Signal Transduction; Stress; Superoxide Dismutase; Superoxides; System; Thick; Tissues; Tubular formation; Vitamin E; Wit; Work; antioxidant therapy; apical membrane; base; concept; in vivo; inhibitor/antagonist; interstitial; liquid chromatography mass spectrometry; normotensive; novel; pressure; response; salt sensitive; tempol; tool

The concept that the kidney plays a dominant role in the long-term control of arterial pressure is based on the pressure-natriuresis. Previous work by our laboratory has indicated that pressure-natriuresis is associated with inhibition of Na+ transport in the proximal tubule and the loop of Henle and identified an important role for elevations in renal medullary blood flow and renal interstitial hydrostatic pressure (RIHP) in signaling this response. However, the mechanism by which elevations in renal perfusion pressure (RPP) and/or RIHP inhibit Na transport is unknown and remains a key unanswered question in hypertension research. Recent studies by our lab and others have revealed that arachidonic acid is primarily metabolized by cytochrome P450 (CYP) enzymes to 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) in the proximal tubule and TALH where these compounds regulate Na+ transport. Thus, the present study will examine the hypothesis that elevations in RPP (through changes in RIHP) increase the production of 20-HETE and/or EETs in the proximal and TALH and that these compounds mediate pressure-natriuresis by inhibiting Na+transport in these nephron segments. Aim 1 will determine whether elevations in RPP and RIHP increase the levels of EETs and 20-HETE in renal interstitial fluid and cortical and medullary tissue using in vivo microdialysis and new fluorescent HPLC and LC/MS assays that we developed for measuring EETs and 20-HETE. Aim 2 will examine the effects of acute and chronic blockade of the synthesis or actions of EETs and 20-HETE on pressure natriuresis and Na in the proximal tubule and TALH using in vivo tubular perfusion. These studies will take advantage of novel specific inhibitors of the synthesis and actions of 20-HETE and EETs that we recently developed in collaboration with Dr. Falck and Tashio Pharmaceutical Corp. This aim will also examine whether 20-HETE and EETs mediate the inhibitory effects of elevations in RPP on Na by inhibiting Na+-K in the proximal tubule and TALH or by altering the distribution of Na+ transporters in the apical membranes of these nephron segments. Aim 3 will characterize the effects of elevations in Na on the levels of EETs and 20-HETE in the kidney of salt-sensitive and salt-resistant strains of rats and whether chronic blockade of the formation of 20-HETE and/or EETs blunts pressure-natriuresis and promotes the development of salt-sensitive hypertension in normotensive strains of rats. Aim 4 will determine if reactive oxygen species (ROS) inhibit the synthesis and enhance the degradation of CYP metabolites of AA in the kidney and whether elevations in the renal levels of CYP metabolites of AA contribute to the antihypertensive effects of antioxidant therapy (TEMPOL or vitamin E) in Dahl SS/Mcw rats. This aim will also examine if ROS-induced decreases in the renal levels of 20-HETE and/or EETs contribute to the development of hypertension in salt-resistant strains of rats when renal oxidative stress is elevated by a chronic renal medullary infusion of the superoxide dismutase inhibitor, DETC. Overall, these studies will provide new information regarding the role of CYP metabolites of AA in renal function, pressure-natriuresis and the long-term control of arterial pressure and the potential interactions of this system in mediating some of the deterimental effects of ROS on renal function. This information will likely provide a strong rationale for the clinical development of inducers of the formation of 20-HETE and/or EETs (fibrates) and stable 20-HETE and EET agonists as new theraputic approaches for the treatment of hypertension and renal disease.

肾脏在动脉压的长期控制中起主导作用的概念是基于压力尿钠。我们实验室之前的工作表明，压力尿钠与近曲小管和亨利袢中 Na+ 转运的抑制有关，并确定了肾髓质血流量和肾间质静水压 (RIHP) 升高在发出这种反应信号中的重要作用。然而，肾灌注压 (RPP) 和/或 RIHP 升高抑制钠转运的机制尚不清楚，并且仍然是高血压研究中尚未解答的关键问题。我们实验室和其他人最近的研究表明，花生四烯酸主要通过细胞色素 P450 (CYP) 酶在近曲小管和 TALH 中代谢为 20-羟基二十碳四烯酸 (20-HETE) 和环氧二十碳三烯酸 (EET)，这些化合物在其中调节 Na+ 转运。因此，本研究将检验 RPP 升高（通过 RIHP 的变化）增加近端 20-HETE 和/或 EET 的产生以及 TALH 和 这些化合物通过抑制这些肾单位段中的 Na+ 转运来介导压力尿钠排泄。目标 1 将使用体内微透析以及我们为测量 EET 和 20-HETE 开发的新荧光 HPLC 和 LC/MS 测定法来确定 RPP 和 RIHP 的升高是否会增加肾间质液以及皮质和髓质组织中的 EET 和 20-HETE 水平。目标 2 将检查急性和慢性阻断 EET 和 20-HETE 的合成或作用对近端肾小管压力尿钠和 Na 的影响，以及 TALH 使用体内肾小管灌注。这些研究将利用我们最近与 Falck 博士和 Tashio Pharmaceutical Corp 合作开发的 20-HETE 和 EET 的合成和作用的新型特异性抑制剂。这一目标还将研究 20-HETE 和 EET 是否通过抑制近曲小管和 TALH 中的 Na+-K 或通过改变这些管顶膜中 Na+ 转运蛋白的分布来介导 RPP 对 Na 升高的抑制作用。 肾单位段。目标 3 将描述钠浓度升高对盐敏感和耐盐大鼠肾脏中 EET 和 20-HETE 水平的影响，以及长期阻断 20-HETE 和/或 EET 的形成是否会减弱 压力尿钠并促进正常血压大鼠盐敏感性高血压的发展。目标 4 将确定活性氧 (ROS) 是否抑制肾脏中 AA CYP 代谢物的合成并增强其降解，以及 AA CYP 代谢物肾脏水平的升高是否有助于 Dahl SS/Mcw 大鼠抗氧化疗法（TEMPOL 或维生素 E）的抗高血压作用。这一目标也将 检查当长期肾髓质输注超氧化物歧化酶抑制剂 DETC 导致肾脏氧化应激升高时，ROS 诱导的 20-HETE 和/或 EET 肾水平降低是否会导致耐盐大鼠患高血压。总体而言，这些研究将提供关于 AA 的 CYP 代谢物在肾功能、压力尿钠排泄和动脉压长期控制中的作用以及该系统在介导 ROS 对肾功能的一些有害影响方面的潜在相互作用的新信息。该信息可能为 20-HETE 和/或 EET（贝特类）形成诱导剂以及稳定的 20-HETE 和 EET 激动剂作为治疗高血压和肾脏疾病的新治疗方法的临床开发提供强有力的理论依据。