Eicosanoids, Vascular Tone and Blood Pressure

描述（由申请人提供）：内皮细胞（EC）释放因子，降低血管张力和对抗血管收缩，包括一氧化氮（NO）和PGI2。在兔主动脉中，通过NO和PG合成抑制剂，乙酰胆碱的内皮依赖性松弛被减少，但不被阻断，这归因于内皮衍生的超极化因子（EDHF）。它们被磷脂酶、脂氧合酶（LOs）和/或细胞色素p450 （CYPs）抑制剂阻断。花生四烯酸（AA）也会引起内皮依赖性松弛和超极化，这些被LO和CYP抑制剂、高[K]o和apamin阻断。因此，这些弛豫和超极化是由AA的LO代谢物介导的。我们已经鉴定出AA的2种血管扩张剂LO代谢物为11(R),12(S),15(S)-三羟基二十碳三烯酸（11,12,15- theta）和一种新型二氢呋喃，15-羟基-11,14-环氧二十碳三烯酸（15- h -11,14- eeta）。11,12,15- theta使兔主动脉松弛，使主动脉平滑肌细胞（SMCs）超极化，激活SMCs阿帕胺敏感的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代谢物可能在调节幼龄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方面发挥重要作用。拟开展的研究将验证花生四烯酸经内皮代谢生成血管扩张性类二十烷酸（包括11、12、15-THETA和15-H- 11、14-EETA）的假说，这些类二十烷酸调节血管张力，介导血管活性激素的作用，调节血压。拟进行的实验将：1。比较天然和合成的15- h -11,14-EETA和11,12,15- theta的血管松弛、色谱行为和作用机制，验证15- h -11,14-EETA和11,12,15- theta通过激活K通道使SMCs松弛和超极化的假设；2. 表征K， 11,12,15- THETA和15- h -11,14- eeta共同释放对血管的影响，并检验K的共同释放增强THETA和HEETA的松弛的假设；3. 表征15- h -11,14- EETA和11,12,15- theta在主动脉、SMCs和ECs中的合成和代谢的生物合成途径；和4。研究LO抑制对幼兔THETA和HEETA合成的年龄依赖性变化以及血压的变化，并验证内源性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.