Eicosanoids, Vascular Tone and Blood Pressure

描述（由申请方提供）：内皮细胞（EC）释放降低血管张力和对抗血管收缩的因子，包括一氧化氮（NO）和PGI 2。在兔主动脉，内皮依赖性舒张乙酰胆碱减少，但不阻断，抑制剂NO和PG合成，并归因于内皮衍生的超极化因子（EDHF）。它们被磷脂酶、脂氧合酶（LO）和/或细胞色素P450（CYP）的抑制剂阻断。花生四烯酸（AA）也会引起内皮依赖性舒张和超极化，这些舒张和超极化可被LO和ERK抑制剂、高[K]o和apamin阻断。因此，这些弛豫和超极化由AA的LO代谢物介导。我们鉴定了AA的两个扩血管LO代谢产物11（R），12（S），15（S）-三羟基二十碳三烯酸（11，12，15-THETA）和一个新的二氢呋喃15-羟基-11，14-环氧二十碳三烯酸（15-H-11，14-EETA）。11，12，15-THETA松弛兔主动脉，使主动脉平滑肌细胞（SMC）超极化，激活SMC apamin敏感性K通道并由乙酰胆碱释放。在幼兔中，这些LO代谢物的合成升高，用LO抑制剂治疗会增加血压。这些LO代谢物可能在调节年轻动物的血压和血流以及介导老年动物对乙酰胆碱和其他激动剂的松弛中是重要的。拟进行的研究将检验以下假设：花生四烯酸被内皮代谢为血管扩张剂类花生酸，包括11，12，15-THETA和15-H-11，14-EETA，其调节血管张力，介导血管活性激素的作用并调节血压。建议的实验将：1。比较天然和合成的15-H-11，14- EETA和11，12，15-THETA的血管舒张、色谱行为和作用机制，并验证15-H-11，14-EETA和11，12，15-THETA通过激活K通道舒张和升高SMC的假设; 2.表征K，11，12，15- THETA和15-H-11，14-EETA的共释放的血管后果，并测试K的共释放增强THETA和HEETA的舒张的假设; 3.表征主动脉、SMC和EC中15-H-11，14- EETA和11，12，15-THETA合成和代谢的生物合成途径;和4.研究THETA和HEETA合成的年龄依赖性变化以及对LO抑制的血压变化，并检验内源性LO代谢物是幼兔血压重要调节因子的假设。

DESCRIPTION (provided by applicant): Endothelial cells (EC) release factors that reduce vascular tone and counteract vasoconstriction including nitric oxide (NO) and PGI2. In the rabbit aorta, endothelium-dependent relaxations to acetylcholine are reduced, but not blocked, by inhibitors of NO and PG synthesis and are attributed to endothelium-derived hyperpolarizing factor (EDHF). They are blocked by inhibitors of phospholipases, lipoxygenases (LOs) and/or cytochrome P450s (CYPs). Arachidonic acid (AA) also causes endothelium-dependent relaxations and hyperpolarizations that are blocked by LO and CYP inhibitors, high [K]o and apamin. Thus, these relaxations and hyperpolarizations are mediated by a LO metabolite of AA. We have identified 2 vasodilator LO metabolites of AA as 11(R),12(S),15(S)- trihydroxy-eicosatrienoic acid (11,12,15-THETA) and a novel dihydro-furan,15-hydroxy-11,14- epoxyeicosatrienoic acid (15-H-11,14-EETA). 11,12,15-THETA relaxes rabbit aorta, hyperpolarizes aortic smooth muscle cells (SMCs), activates a SMC apamin-sensitive K channel and is released by acetylcholine. In young rabbits, the synthesis of these LO metabolites is elevated and treatment with a LO inhibitor increases blood pressure. These LO metabolites may be important in regulating blood pressure and blood flow in young animals and mediating relaxations to acetylcholine and other agonists in older animals. The proposed studies will test the hypothesis that arachidonic acid is metabolized by the endothelium to vasodilator eicosanoids, including 11,12,15-THETA and 15-H- 11,14-EETA, that regulate vascular tone, mediate the action of vasoactive hormones and regulate blood pressure. The proposed experiments will: 1. Compare the natural and synthetic 15-H-11,14- EETA and 11,12,15-THETA for vasorelaxation, chromatographic behavior and mechanism of action and test the hypothesis that 15-H-11,14-EETA and 11,12,15-THETA relax and hyperpolarize SMCs by activating K channels; 2. Characterize the vascular consequences of the co-release of K, 11,12,15- THETA and 15-H-11,14-EETA and test the hypothesis that the co-release of K enhances the relaxations to the THETA and HEETA; 3. Characterize the biosynthetic pathway(s) for 15-H-11,14- EETA and 11,12,15-THETA synthesis and metabolism in aorta, SMCs and ECs; and 4. Investigate the age-dependent changes in the THETA and HEETA synthesis and changes in blood pressure in response to LO inhibition and test the hypothesis that endogenous LO metabolites are important regulators of blood pressure in young rabbits.