ARACHIDONATE OMEGA 1 HYDROXYLATION IN HYPERTENSION

高血压中的花生四烯酸 Omega 1 羟基化

• 批准号: 6109762
• 负责人: Michal Laniado Schwartzman
• 金额: $ 24.35万
• 依托单位: NEW YORK MEDICAL COLLEGE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 1999-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6109762
• 关键词: arachidonate; cytochrome P450; dietary sodium; disease /disorder model; fatty acid metabolism; gas chromatography mass spectrometry; gene expression; hydroxylation; hypertension; ion transport; isolation perfusion; isozymes; messenger RNA; nucleic acid probes; polymerase chain reaction; potassium channel; protein isoforms; renal tubule; sodium; spontaneous hypertensive rat; western blottings

20-HETE is a major cytochrome p450 (CYP) arachidonic acid (AA) metabolite in renal structures including proximal tubules, TALH and microvessels. 20- HETE has potent effects on the vasculature (vasoconstriction of renal arterioles) and tubules (inhibition of ion transport and K+ channel activity). It may, therefore, affect pro- and/or anti-hypertensive mechanisms. For example, an increase in 20-HETE synthesis in renal microvessels would bring about an increased vasoconstriction mechanisms influencing prohypertensive mechanism characterized by elevated vascular tone, increased GFR and RBF and sodium retention. On the other hand, increased tubular 20-HETE synthesis (proximal, TALH, macula densa) would be conducive to an increase in antihypertensive mechanisms operating at the level of regulation of salt and water balance and characterized by natriuresis and diuresis. The SHR is particularly interesting since it displays high (over expression) renal 20-HETE production. Furthermore, the development of hypertension in this model occurs between 5 and 9 weeks of age having been preceded by a many-fold increase in renal 20-HETE synthesis between 3 and 5 weeks. Inhibition of 2O-HETE synthesis in this stage is associated with blood pressure reduction suggesting a role for 20-HETE in the development of hypertension. This unique increase of 20- HETE production suggests the involvement of a distinct CYP isozyme(s) that is under regulatory control and that specifically metabolizes AA to 20- HETE. The CYP4A isoforms (4A1, 4A2 and 4A3), all of which are present in the rat kidney, are believed to be capable of metabolizing AA at the omega-carbon to yield 20-HETE. These isoforms, although sharing 66-98% homology, are localized to different renal structures and are exposed to different regulatory mechanisms. 20-HETE synthesis may be derived from different CYP4A isozymes in tubules and vessels. Alternatively, it may be formed by the same isozyme or a mixture of all three that are influenced by different regulatory elements. To understand the regulatory mechanisms underlying the renal synthesis of this important eicosanoid, we will characterize and correlate CYP4A protein and mRNA expression to AA omega- hydroxylation in tubular and vascular preparations from hypertensive and normotensive rats and study the influence of dietary salt. The contribution of CYP4A protein to 20-HETE synthesis in the kidney will be assessed by molecular cloning and expression of each isozyme following with analysis of its catalytic activity. The results of the proposed study will provide the biochemical basis for evaluating the functional significance of renal 20-HETE.

20-HETE是一种主要的细胞色素p450（α）花生四烯酸（AA）代谢产物 肾脏结构包括近端小管、TALH和微血管。20- HETE对血管系统（肾脏的血管收缩）具有强效作用。 小动脉）和小管（抑制离子转运和K+通道 活动）。因此，它可能会影响促高血压和/或抗高血压 机制等 例如，肾脏中20-HETE合成的增加， 微血管会增加血管收缩机制， 影响以血管升高为特征的促高血压机制 紧张，增加GFR和RBF和钠潴留。另一方面，在一项研究中， 肾小管20-HETE合成增加（近端、TALH、致密斑）将 有助于增加抗高血压机制， 盐和水平衡的调节水平，其特征在于： 尿钠排泄和利尿。SHR特别有趣，因为它 显示高（过表达）肾20-HETE产生。而且 在该模型中，高血压的发展发生在5至9周之间， 年龄之前肾20-HETE增加了许多倍 3 - 5周合成。抑制2 O-HETE合成， 阶段与血压降低相关，表明 20-HETE在高血压发展中的作用。这一独特的增长20- HETE的产生表明涉及一种独特的同工酶， 在监管控制下，特异性地将AA代谢为20- HETE。CYP 4A亚型（4A 1、4A 2和4A 3）均存在于 大鼠肾脏，被认为是能够代谢AA在 ω-碳以产生20-HETE。这些异构体，虽然共享66-98% 同源性，定位于不同的肾结构，并暴露于 不同的监管机制。20-HETE合成可以衍生自 不同的CYP 4A同工酶在肾小管和血管。或者，它可以是 由相同的同工酶或受影响的所有三种同工酶的混合物形成 不同的监管机构。为了了解监管机制， 在肾脏合成这种重要的类二十烷酸的基础上，我们将 表征CYP 4A蛋白和mRNA表达并将其与AA ω- 高血压和高血压患者肾小管和血管制备物中羟化 正常血压大鼠，并研究膳食盐的影响。的 CYP 4A蛋白对肾脏中20-HETE合成的贡献将是 通过分子克隆和每种同工酶的表达进行评估， 并对其催化活性进行了分析。拟议研究的结果 将为评价功能性 肾脏20-HETE意义