Blackwell Katherine A, Sorenson Joseph P, Richardson Darcy M, Smith Leslie A, Suda Osamu, Nath Karl, Katusic Zvonimir S
Department of Anesthesia Research and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Am J Physiol Heart Circ Physiol. 2004 Dec;287(6):H2448-53. doi: 10.1152/ajpheart.00248.2004. Epub 2004 Aug 19.
Oxidative stress has been implicated as an important mechanism of vascular endothelial dysfunction induced by aging. Previous studies suggested that tetrahydrobiopterin (BH4), an essential cofactor of endothelial NO synthase, could be a molecular target for oxidation. We tested the hypothesis that oxidative stress, in particular oxidation of BH4, may contribute to attenuation of endothelium-dependent relaxation in aged mice. Vasomotor function of isolated carotid arteries was studied using a video dimension analyzer. Vascular levels of BH4 and its oxidation products were measured via HPLC. In aged mice (age, 95 +/- 2 wk), endothelium-dependent relaxation to ACh (10(-5) to 10(-9) M) as well as endothelium-independent relaxation to the NO donor diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-5) to 10(-9) M) were significantly reduced compared with relaxation detected in young mice (age, 23 +/- 0.5 wk). Incubation of aged mouse carotid arteries with the cell-permeable SOD mimetic Mn(III)tetra(4-benzoic acid)porphyrin chloride normalized relaxation to ACh and DEA-NONOate. Furthermore, production of superoxide anion in aorta and serum levels of amyloid P component, which is the murine analog of C-reactive protein, was increased in old mice. In aorta, neither the concentration of BH4 nor the ratio of reduced BH4 to the oxidation products were different between young and aged mice. Our results demonstrate that in mice, aging impairs relaxation mediated by NO most likely by increased formation of superoxide anion. Oxidation of BH4 does not appear to be an important mechanism underlying vasomotor dysfunction in aged mouse arteries.
氧化应激被认为是衰老诱导血管内皮功能障碍的重要机制。先前的研究表明，四氢生物蝶呤（BH4）作为内皮型一氧化氮合酶的必需辅因子，可能是氧化的分子靶点。我们验证了以下假说：氧化应激，尤其是BH4的氧化，可能导致老年小鼠内皮依赖性舒张功能减弱。使用视频尺寸分析仪研究了离体颈动脉的血管舒缩功能。通过高效液相色谱法测定血管中BH4及其氧化产物的水平。与年轻小鼠（年龄，23±0.5周）相比，老年小鼠（年龄，95±2周）对乙酰胆碱（10⁻⁵至10⁻⁹M）的内皮依赖性舒张以及对一氧化氮供体二乙铵（Z）-1-（N，N-二乙氨基）重氮-1-鎓-1,2-二醇盐（DEA-NONOate，10⁻⁵至10⁻⁹M）的非内皮依赖性舒张均显著降低。用可透过细胞的超氧化物歧化酶模拟物四（4-苯甲酸）锰（III）卟啉氯化物孵育老年小鼠颈动脉，可使对乙酰胆碱和DEA-NONOate的舒张功能恢复正常。此外，老年小鼠主动脉中超氧阴离子的产生以及血清中淀粉样蛋白P成分（C反应蛋白的小鼠类似物）水平升高。在主动脉中，年轻和老年小鼠之间BH4的浓度以及还原型BH4与氧化产物的比例均无差异。我们的结果表明，在小鼠中，衰老最有可能通过超氧阴离子形成增加而损害一氧化氮介导的舒张。BH4的氧化似乎不是老年小鼠动脉血管舒缩功能障碍的重要潜在机制。
