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

花生四烯酸(AA)的肾脏代谢产生多种不同的 有效调节肾脏的生物活性脂质介体 血流动力学和离子沿肾单位的传输。环氧合酶介导 前列腺素的形成已经得到了广泛的研究，并且是一个重要的 生理作用，已经确立。肾脏还具有强大的细胞色素。 快速代谢花生四烯酸的P450(CYP450)系统 生物活性脂质，包括环氧二十碳三烯酸(EETs)和 Omega/omega-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细胞色素P450与血管内膜的联系 活动和全身血压的调节。抑制 肾脏细胞色素P450活性导致高血压和细胞色素P450氨基酸代谢产物， 20-HETE抑制粗大升肢(TAL)的CI吸收。20-HETE 是由少数几个细胞色素P450组成的，而细胞色素P4A家族似乎 是肾脏中的相关异构体。在具体目标#1中，我们建议 鉴定特定的细胞色素P4A亚型及其omega/omega-1的作用 AA代谢产物对微灌注厚小鼠体内离子转运的调节作用 升肢(TAL)。靶向干扰细胞色素P4A10基因的小鼠实验研究 和4A14应该允许我们定义特定的CYP450亚型在 调节TAL离子转运。细胞色素P4A的表达最近被认为是 显示在脂肪酸激活的转录控制下 因子，称为过氧化物酶体增殖物激活受体α (PPARAlpha)。我们最近绘制了三个基因在肾脏内的表达 PPAR亚型(PPARAlpha、Gamma和Delta)，并发现PPARAlpha高度 表达于近端小管和TAL，而PPAR-γ主要表达于 在收集管道中表达。初步数据显示激活和 Tal，而PPAR-Gamma则增强集合管对Na的吸收。在……里面 具体目标#2，我们建议表征PPAR激活的影响 培养的大脑皮层集合管上皮钠转运的研究 以及整个动物的钠平衡研究。最后，生产 EETs是由不同的细胞色素P450家族介导的，包括细胞色素P450和 CYP2B亚型证据表明5，6-EET和14，15-EET具有潜在的调节作用 在肾脏集合管中的运输。在具体目标#3中，我们建议 进一步研究细胞色素P450氨基酸环氧合酶在离子调节中的作用 沿肾单位运输。前列腺素EP1受体在血管紧张素转换酶中的作用 将测试5，6-EET在微灌注型CCDs中的作用，如 腺病毒介导的细胞色素P450基因表达对细胞转运的影响 培养的ccd。我们希望这些研究将有助于确定 细胞色素P450-氨基酸代谢在调节肾离子转运中的作用及其对钠离子的影响 排泄，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.