内皮型一氧化氮合酶激活导致小鼠脑动脉中产生扩张性过氧化氢。
Endothelial nitric oxide synthase activation leads to dilatory H2O2 production in mouse cerebral arteries.
作者信息
Drouin Annick, Thorin-Trescases Nathalie, Hamel Edith, Falck John R, Thorin Eric
机构信息
Université de Montréal, Department of Surgery and Research Center, Institut de Cardiologie de Montréal, Montréal, Québec, Canada.
出版信息
Cardiovasc Res. 2007 Jan 1;73(1):73-81. doi: 10.1016/j.cardiores.2006.10.005. Epub 2006 Oct 13.
OBJECTIVE
Hydrogen peroxide (H2O2) produced by the vascular endothelium is a signaling molecule regulating vascular tone. We hypothesized that H2O2 derived from eNOS activity could play a physiological role in endothelium-dependent dilation of mouse cerebral arteries.
METHODS
Simultaneous endothelium-dependent dilation and fluorescence-associated free radical (DCF-DA) or NO (DAF-2) production were recorded in isolated and pressurized (60 mm Hg) cerebral artery of C57Bl/6 male mice.
RESULTS
Without synergism, N-nitro-L-arginine (L-NNA) or the H2O2 scavengers catalase, PEG-catalase and pyruvate reduced (P < 0.05) by 50% the endothelium-dependent dilation induced by acetylcholine (ACh). Simultaneously with the dilation, H2O2--but not NO--production, sensitive to either L-NNA or catalase, was detected. In cerebral arteries from C57Bl/6.eNOS-/- mice, catalase had no effect on ACh-induced dilation and no H2O2-associated fluorescence was observed. In C57Bl/6 mice, silver diethyldithiocarbamate (DETC), a superoxide dismutase (SOD) inhibitor, but not the specific NO scavenger 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl3-oxide (PTIO), prevented ACh-induced dilation and H2O2 production suggesting that eNOS-derived superoxide is an intermediate in the production of H2O2. The catalase-sensitive ACh-induced dilation was restored by the eNOS cofactor tetrahydrobiopterin (BH4). This reversal was associated with a NO-associated fluorescence sensitive to PTIO but not to catalase. Soluble guanylate cyclase inhibition with 1H-[1,2,4]-oxadiazole-4,3-aquinoxalin-1-one (ODQ) prevented the dilation induced by ACh and by exogenous H2O2. Lastly, L-NNA, PTIO and ODQ--but not DETC, catalase or pyruvate--increased the pressure-dependent myogenic tone, suggesting that eNOS produces NO at rest, but leads to H2O2 during muscarinic stimulation.
CONCLUSION
H2O2-dependent dilation in mouse cerebral arteries appears to be a physiological eNOS-derived mechanism.
目的
血管内皮产生的过氧化氢（H₂O₂）是一种调节血管张力的信号分子。我们推测，由内皮型一氧化氮合酶（eNOS）活性产生的H₂O₂可能在小鼠脑动脉内皮依赖性舒张中发挥生理作用。
方法
在分离并加压至60毫米汞柱的C57Bl/6雄性小鼠脑动脉中，同时记录内皮依赖性舒张以及荧光相关自由基（2',7'-二氯二氢荧光素二乙酸酯，DCF-DA）或一氧化氮（NO，二氨基荧光素-2，DAF-2）的产生情况。
结果
在无协同作用的情况下，N-硝基-L-精氨酸（L-NNA）或H₂O₂清除剂过氧化氢酶、聚乙二醇化过氧化氢酶和丙酮酸可使乙酰胆碱（ACh）诱导的内皮依赖性舒张降低（P < 0.05）50%。在舒张同时，检测到对L-NNA或过氧化氢酶敏感的H₂O₂产生，但未检测到NO产生。在C57Bl/6.eNOS基因敲除小鼠的脑动脉中，过氧化氢酶对ACh诱导的舒张无影响，且未观察到与H₂O₂相关的荧光。在C57Bl/6小鼠中，超氧化物歧化酶（SOD）抑制剂二乙基二硫代氨基甲酸银（DETC）可阻止ACh诱导的舒张和H₂O₂产生，而特异性NO清除剂2-苯基-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物（PTIO）则无此作用，这表明eNOS衍生的超氧化物是H₂O₂产生的中间产物。eNOS辅因子四氢生物蝶呤（BH4）可恢复过氧化氢酶敏感的ACh诱导的舒张。这种逆转与对PTIO敏感但对过氧化氢酶不敏感的NO相关荧光有关。用1H-[1,2,4] -恶二唑并[4,3-a]喹喔啉-1-酮（ODQ）抑制可溶性鸟苷酸环化酶可阻止ACh和外源性H₂O₂诱导的舒张。最后，L-NNA、PTIO和ODQ（而非DETC、过氧化氢酶或丙酮酸）可增加压力依赖性肌源性张力，这表明eNOS在静息时产生NO，但在毒蕈碱刺激时导致H₂O₂产生。
结论
小鼠脑动脉中依赖H₂O₂的舒张似乎是一种由eNOS衍生的生理机制。
Zotero 插件