压力负荷性左室肥厚代偿期左心室基质金属蛋白酶-2活性与氧化应激的关系

Relationship between the activity of matrix metalloproteinase-2 and oxidative stress in compensated phase of pressure overloaded left ventricular hypertrophy

【目的】探讨高血压性左心室肥厚代偿期左心室基质金属蛋白酶-2(matrix metalloproteinase-2,MMP-2)蛋白含量以及活性变化与氧化应激的关系。【方法】动物模型采用7周龄雄性卒中易感性自发性高血压大鼠(stroke-prone spontaneously hypertensive rats,SHR-SPs);并以同龄Wistar-Kyoto大鼠(WKY)作为正常血压对照。12周后对所有大鼠行有创血流动力学检测和离体压力容积曲线分析;心室组织一部分用于石蜡包埋进行病理学分析,另一部分用于组织活性氧簇(reactive oxygen species,ROS)水平测定。心室组织MMP-2活性检测采用明胶酶谱分析,蛋白含量检测采用Western blotting法。【结果】SHR-SPs于19周龄时左心室重量指数明显高于WKY大鼠[(4.55±0.39)mg/g vs(3.25±0.35)mg/g,P<0.05)],心肌细胞出现明显增大。LV胶原沉积量明显增多,在偏振光显微镜下表现为黄色和红色纤维增多。血流动力学分析显示此时SHR-SPs左室舒张末压增加[(15.2±1.5)mmHg vs(8.1±1.0)mmHg],dp/dtmax基本正常。SHR-SPs左心室ROS水平明显升高。虽然MMP-2蛋白表达水平较WKY升高1.5倍,但是MMP-2的明胶酶活性可升高4倍以上。【结论】MMP-2蛋白表达上调和活性增高之间变化的不一致性,与ROS中介的MMP-2非酶解激活途径有关,并在高血压性左心室重塑中具有重要的病理生理学意义。

[ Objective] To investigate the relationship between the activity of matrix metal]oproteinase-2 （MMP-2） and oxidative stress in compensated phase of pressure overloaded left ventricular hypertrophy. [Methods] 7 week-old male stroke-prone sponta- neously hypertensive rats （SHR-SPs）, and age-matched male Wistar-Kyoto rats （WKY rats） were used. 12 weeks later, all rats were underwent invasive hemodynamic analysis and subject to ex vivo pressure-volume relationship analysis. Rats were then sacri- ficed, and the hearts were prepared for histopathological and biochemical analysis. Tissue level of reactive oxygen species （ROS） were also determined by colourimetrical method. Activity and protein content of MMP-2 were determined by gelatin-zymography and Western blotting, respectively. [ Results] 19 week-old SHR-SPs exhibited compensated phase of pressure overloaded left ventricular hypertrophy, as revealed by enlarged cardiomyocytes,excessive collagen accumulation, compromised diastolic function and partially preserved systolic performance, with relatively normal left ventricular chamber size. These alterations was accompa nied by increased production of tissue ROS. MMP-2 protein content was increased by 1.5 folds in SHR-SPs. However, gelatinolyric activity d MMP-2 was increased by more than 4 fold as compared with WKY rats. [Conclusions] The increased up-regulation of MMP-2 activity is due to the non-pmteolytic activation mechanism by over-production of ROS, which plays an important role in the pathogenesis of pressure overloaded ventricular remodeling.