Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 67, 56100 Pisa, Italy.
Hypertension. 2013 Aug;62(2):337-44. doi: 10.1161/HYPERTENSIONAHA.111.00995. Epub 2013 Jun 3.
Essential hypertensive patients show a reduced nitric oxide availability secondary to oxidative stress generation in peripheral microcirculation. Cyclooxygenase (COX) contributes to reduce nitric oxide availability. We assessed the possible vascular sources of oxidative stress, including COX-1, COX-2, and nicotinamide adenine dinucleotide phosphate oxidase, as determinants of endothelial dysfunction in small arteries isolated from essential hypertensive patients or normotensive controls. Small arteries were dissected after subcutaneous fat biopsies and evaluated on a pressurized micromyograph. Endothelium-dependent vasodilation was assessed by acetylcholine, repeated under NG-nitro-l-arginine methyl ester, SC-560 (COX-1 inhibitor), DuP-697 (COX-2 inhibitor), ascorbic acid, or the nicotinamide adenine dinucleotide phosphate oxidase inhibitors apocynin or diphenylene iodonium. Vascular oxidative stress generation (fluorescent dihydroethidium), COX-1 and COX-2 expression (Western blot), and localization (immunohistochemistry) were also assessed. In controls, response to acetylcholine was blunted by NG-nitro-l-arginine methyl ester (P<0.001) and unmodified by SC-560, DuP-697, or ascorbic acid. In hypertensive patients, relaxation to acetylcholine was blunted, resistant to NG-nitro-l-arginine methyl ester or SC-560, and enhanced (P<0.01) by DuP-697, apocynin, or diphenylene iodonium (P<0.05). Furthermore, in hypertensive patients, response to acetylcholine was normalized by ascorbic acid or apocynin+DuP-697. Intravascular oxidative stress generation was enhanced in hypertensive patients, decreased (P<0.01) by DuP-697, partly attenuated by apocynin or diphenylene iodonium, and prevented by ascorbic acid. Enhanced COX-2 expression and localization in the vascular media of hypertensive patients were also detected. In small resistance arteries of essential hypertensive patients, COX-2 is overexpressed and reduces nitric oxide availability. COX-2 represents a major source of oxidative stress generation, whereas nicotinamide adenine dinucleotide phosphate oxidase plays a minor, but significant, role in promoting superoxide generation.
原发性高血压患者外周微循环产生氧化应激，导致一氧化氮供应减少。环氧化酶（COX）有助于减少一氧化氮的供应。我们评估了可能的血管氧化应激来源，包括 COX-1、COX-2 和烟酰胺腺嘌呤二核苷酸磷酸氧化酶，作为从原发性高血压患者或正常血压对照者分离的小动脉内皮功能障碍的决定因素。小动脉在皮下脂肪活检后被解剖，并在加压微测功仪上进行评估。乙酰胆碱评估内皮依赖性血管舒张，在 NG-硝基-L-精氨酸甲酯、SC-560（COX-1 抑制剂）、DuP-697（COX-2 抑制剂）、抗坏血酸或烟酰胺腺嘌呤二核苷酸磷酸氧化酶抑制剂 apocynin 或二苯基碘重复下进行。血管氧化应激产生（荧光二氢乙啶）、COX-1 和 COX-2 表达（Western blot）和定位（免疫组织化学）也进行了评估。在对照组中，乙酰胆碱的反应被 NG-硝基-L-精氨酸甲酯（P<0.001）减弱，而不受 SC-560、DuP-697 或抗坏血酸的影响。在高血压患者中，乙酰胆碱的松弛作用减弱，对 NG-硝基-L-精氨酸甲酯或 SC-560 有抗性，但被 DuP-697、apocynin 或二苯基碘增强（P<0.05）。此外，在高血压患者中，乙酰胆碱的反应通过抗坏血酸或 apocynin+DuP-697 被正常化。血管内氧化应激产生在高血压患者中增强，被 DuP-697 降低（P<0.01），被 apocynin 或二苯基碘部分减弱，并被抗坏血酸阻止。还检测到高血压患者血管中层 COX-2 表达和定位增强。在原发性高血压患者的小阻力动脉中，COX-2 过度表达并减少一氧化氮的供应。COX-2 是氧化应激产生的主要来源，而烟酰胺腺嘌呤二核苷酸磷酸氧化酶在促进超氧化物产生方面作用较小，但意义重大。
