过氧亚硝基阴离子分解催化剂对衰老大鼠血管舒张功能的保护作用

Peroxynitrite decomposition catalyst improves vascular dysfunction in aging rats

目的利用过氧亚硝基阴离子（ONOO^-）分解催化剂FeTMPyP探讨衰老大鼠血管舒张功能障碍的可能机制。方法选取雄性SD大鼠，随机分为成年组（3-4月，n=8）、衰老组（18-20月，n=8）及给予FeTMPyP的衰老组（n=6）；制备离体胸主动脉环，观察血管舒张功能；采用免疫组织化学法和Westernblot法测定血管组织中可代表ONOO^-生成的标记物3-硝基酪氨酸（3-NT）的表达。结果与成年组大鼠比较，衰老组大鼠胸主动脉环对10^-9-10^-5mol／L累积浓度的内皮依赖性舒张剂乙酰胆碱（ACh）的最大舒张程度显著下降[（29．74％±8．28％）vs（69．52％±5．51％），P〈0．001]；对10^-9-10^-5mol/L累积浓度的非内皮依赖性舒张剂硝普钠（SNP）的最大舒张程度也显著下降[（92．01％±3．19％）vs（99．26％±1．33％），P〈0．001]。与成年组大鼠比较，衰老组大鼠血管组织中3-NT蛋白表达增加（P〈0．05）。给予FeTMPyP后，衰老大鼠血管组织中3-NT蛋白表达下降（P〈0．01）；抑制ONOO^-的生成后，衰老大鼠胸主动脉环对累积浓度ACh的最大舒张程度显著升高[（65．96％±11．36％）vs（29．74％±8．28％），P〈0．001]，对累积浓度SNP的最大舒张程度也显著升高[（98．15％±2．79％）vs（92．01％±3．19％），P〈0．001]。结论FeTMPyP改善了衰老大鼠血管舒张功能，提示ONOO^-可能在衰老大鼠血管功能障碍中起重要作用。

Objective To investigate the possible mechanisms of aging-associated vascular dysfunction by peroxynitrite （ONTO^-） decomposition catalyst FeTMPyP. Methods Male Sprague-Dawlew （SD） rats were randomly divided into three groups： adult group （3-4-month-old, n=8）, aging group （18-20-month-old, n=8）, and FeTMPyP treatment aging group （n=6）. The thoracic aorta was isolated for measurement of vascular diastolic function. Immunohistochemistry and Western-blot were performed to determine the expression of 3-nitrotyrosine （3-NT, a marker of ONTO^- formation） in thoracic aortic arteries. Results （1） Comparing with adult group, the maximal vasodilation in aging rats induced by acetylcholine （ACh, an endothelium-dependent vasodilator, 10^-9 to 10^-5 mol/L） was significantly decreased from （69.52% ± 5.51%） to （29.74% ± 8.28%） （P 〈 0.001）; the maximal vasodilation induced by sodium nitroprusside （SNP, an endothelium-independent vasodilator, 10^-9to 10^-5 mol/L） was also decreased from （99.26% ±1.33%） to （92.01% ±3.19%） （P 〈 0.001）. （2） The expression of 3-NT in aging vascular tissues was increased （P 〈 0.05） compared with adult group. （3） In aging rats treated with FeTMPyP, the expression of 3-NT was decreased （P 〈 0.01）. Moreover, FeTMPyP significantly improved vascular endothelium- dependent and endothelium-independent vasodilations in aging rats. After inhibiting the generation of ONTO^-, ACh-induced maximal vasorelaxation was markedly increased [（65.96% ± 11.36%） vs （29.74% ± 8.28%）, P 〈 0.001] and SNP-induced maximal vasodilation was also increased [（98.15% ± 2.79%） vs （92.01% ± 3.19%）, P 〈 0.001]. Conclusion FeTMPyP can improve vasodilation dysfunction in aging rats, suggesting that ONTO- may play an important role in aging-related vascular dysfunction.