CYTOCHROME P-450 ARACHIDONIC ACID METABOLISM & REGULATION OF RENAL ION TRANSPORT

花生四烯酸（AA）的肾代谢产生多种不同的代谢产物， 有效调节肾功能的生物活性脂质介质 血液动力学和离子运输沿着肾单位。环氧合酶介导 前列腺素的形成已被广泛研究， 生理作用，建立。肾脏也有一个强大的细胞色素 P450（CYP 450）系统，可将花生四烯酸快速代谢为几种 - 生物活性脂质，包括环氧二十碳三烯酸（Epoxyeicosatrienoic Acids，ESTs）， ω/ω-1 AA代谢物（羟基二十碳四烯酸或HETE）。 越来越多的证据支持肾脏CYP 450 活动和调节全身血压。抑制 肾脏CYP 450活性诱导高血压和CYP 450 AA代谢物， 20-HETE抑制粗升支（TAL）中的CI吸收。20-HETE 仅由少数CYP 450积极形成，CYP 4A家族似乎 是肾脏中的相关亚型。在具体目标#1中，我们建议 表征特定CYP 4A亚型及其omega/omega-1的作用 AA代谢产物对小鼠微灌流心肌细胞离子转运的调节作用 上行支（TAL）。小鼠中CYP 4A 10靶向破坏的研究 和4A 14应该允许我们定义特定CYP 450亚型在 调节TAL离子转运。CYP 4As的表达最近被 显示在脂肪酸激活转录的控制下 过氧化物酶体增殖物激活受体α（peroxisome proliferator activated receptor alpha） （PPARalpha）。我们最近绘制了三种肾脏内表达的 PPARalpha、gamma和delta，发现PPARalpha是一种高表达的过氧化物酶体。 在近端小管和TAL中表达，而PPARgamma主要在近端小管和TAL中表达。 在集合管中表达。初步数据表明激活， TAL，而PPARgamma增强集合管中Na+的吸收。在 具体目标#2，我们建议表征PPAR激活的影响 对培养的皮质集合管上皮Na+转运的影响 以及在整个动物Na+平衡研究中。以及提交 Ehrs由不同的CYP 450家族介导，包括CYP 2C和 CYP 2B亚型证据表明5，6-EET和14，15-EET有效调节 在肾集合管中运输。在具体目标#3中，我们建议 进一步研究CYP 450 AA表氧化酶在调节离子 沿着肾单位运输。前列腺素EP 1受体在 将测试介导微灌注CCD中5，6-EET的作用， 腺病毒介导的CYP 450表达对细胞内转运的影响 培养的CCD。我们希望这些研究将有助于确定 CYP 450-AA代谢调节肾脏离子转运及其对Na+的影响 排泄，并最终控制全身血压。

The renal metabolism of arachidonic acid (AA) produces a diverse array of biologically active lipid mediators which potently regulate renal hemodynamics and ion transport along the nephron. Cyclooxygenase mediated prostanoid formation has been extensively studied and an important physiologic role, established. The kidney also possess a robust cytochrome P450 (CYP450) system which rapidly metabolizes arachidonate to several bioactive lipids including the epoxyeicosatrienoic acids (EETs) and omega/omega-1 AA metabolites (the hydroxyeicosatetraenoic acids or HETEs). Accumulating evidence supports an intimal association between renal CYP450 activity and the regulation of systemic blood pressure. Inhibition of renal CYP450 activity induces hypertension and the CYP450 AA metabolite, 20-HETE inhibits CI-absorption in the thick ascending limb (TAL). 20-HETE is actively formed by only a few CYP450s, and the CYP4A family appear to be the relevant isoforms in the kidney. In specific aim #1 we propose to characterize the role of specific CYP4A isoforms and their omega/omega-1 AA metabolites in regulating ion transport to murine microperfused thick ascending limbs (TAL). Studies in mice with targeted disruption of CYP4A10 and 4A14 should allow us to define roles for specific CYP450 isoforms in regulating TAL ion transport. The expression of CYP4As has recently been shown to be under the control of a fatty acid activated transcription factor, known as peroxisome proliferator activated receptor alpha (PPARalpha). We have recently mapped the intra-renal expression of three PPAR isoforms (PPARalpha, gamma, and delta) and find PPARalpha is highly expressed in proximal tubule and TAL, whereas PPARgamma is primarily expressed in the collecting duct. Preliminary data suggests activation and TAL, whereas PPARgamma enhances Na+ absorption in collecting duct. In specific aim #2, we propose to characterize the effects of PPAR activation on epithelial Na+ transport in cultured cortical collecting ducts (CCDs) as well as in whole animal Na+ balance studies. Finally, the production of the EETs is mediated by distinct families of CYP450s including CYP2C and CYP2B isoforms Evidence suggests 5,6-EET and 14,15-EET potently regulate transport in the renal collecting duct. In specific aim #3 we propose to further examine the role of CYP450 AA epoxygenases in regulating ion transport along the nephron. Roles for the prostaglandin EP1 receptor in mediating the effect of 5,6-EET in microperfused CCDs will be tested, as will effects of adenoviral mediated CYP450 expression on transport in cultured CCDs. It is our hope these studies will help define the role of CYP450-AA metabolism in regulating renal ion transport, its impact on Na+ excretion, and ultimately the control of systemic blood pressure.