ARACHIDONATE OMEGA 1 HYDROXYLATION IN HYPERTENSION

20-HETE是细胞色素P450(CYP)花生四烯酸(AA)的主要代谢物 在肾脏结构中，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)有很强的作用 小动脉)和小管(抑制离子转运和K+通道 活动)。因此，它可能会影响高血压的前驱和/或抗高血压 机械装置。例如，肾脏中20-HETE合成的增加 微血管会带来血管收缩机制的增强 影响以血管升高为特征的高血压发病机制 音调、GFR、RBF和钠滞留增加。另一方面， 增加小管20-HETE的合成(近端、TALH、致密黄斑)将 有利于增加降压机制在 盐水平衡的调节水平，其特征是 利钠和利尿。SHR特别有趣，因为它 显示高(过度表达)肾20-HETE产物。此外， 在这个模型中，高血压的发生在5到9周之间 在年龄之前，肾脏20-HETE增加了许多倍 合成在3到5周之间。抑制HETE合成的实验研究 分期与血压降低有关，这表明 20-HETE在高血压发病中的作用这种独特的20%的增长- HETE的产生表明参与了一种独特的CYP同工酶(S) 处于监管控制之下，并专门代谢AA至20- HETE.CYP4A亚型(4A1、4A2和4A3)，所有这些亚型都存在于 大鼠的肾脏被认为能够在体内代谢AA 欧米茄-碳产生20-HETE。这些异构体虽然有66%-98%的共同点 同源物，定位于不同的肾脏结构，并暴露于 不同的监管机制。20-HETE的合成可从 肾小管和血管中不同的细胞色素P4A同工酶。或者，它可能是 由相同的同工酶或受影响的所有三种酶的混合物形成的 通过不同的监管要素。要了解监管机制 在肾脏合成这种重要的二十烷类化合物的基础上，我们将 细胞色素P4A蛋白和mRNA表达与AA-omega-1的关系 高血压病患者肾小管和血管中羟化作用的研究 正常血压大鼠，研究饮食盐对其的影响。这个 CYP4A蛋白对肾脏20-HETE合成的贡献将是 通过以下各同工酶的分子克隆和表达进行评估 并分析了其催化活性。拟议研究的结果 将为评估功能提供生化基础 肾20-HETE测定的临床意义

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.