基质金属蛋白酶9在大鼠单纯收缩期高血压模型发生中的作用

Matrix metalloproteinase-9 in rat model of isolated systolic hypertension

目的 研究基质金属蛋白酶9（MMP-9）在单纯收缩期高血压形成中的作用.方法 选用8周龄Wistar 雄性大鼠20只作为研究对象,随机分成两组,模型组（n=10）和对照组（n=10）.应用华法林和维生素K1诱导动脉中层钙化,8周后右侧颈动脉插管进行有创血压和心室内压力的检测.以及取材主动脉,Von Kossa染色分析动脉钙化程度；采用原子吸收光谱法测定血管组织中钙含量.采用弹性纤维染色法观察主动脉组织中弹性纤维形状；应用免疫组织化学和Western blot检测主动脉组织中MMP-9的表达水平.结果 模型组大鼠血压与对照组相比明显增高[收缩压：（ 151±9） vs （113±7） mmHg,P＜0.01,舒张压：（122±10） vs （98±8） mmHg,P＜0.05]；而各组间平均左室内压无明显变化.模型组大鼠血压变化的同时伴有动脉形态结构的改变,主动脉和颈动脉中层钙化明显,模型组主动脉钙含量明显高于对照组[（17.9±1.8）vs（5.8±0.6）mg/g,P＜0.01].弹力纤维断裂变直,失去波浪形状.Western免疫印迹法分析模型组MMP-9蛋白表达较对照组明显升高.结论 利用华法林和维生素K1诱导的单纯收缩期高血压大鼠是可重复性好,便捷,以及与人体衰老相似较为理想的模型.MMP-9酶表达明显增多可促使大动脉中层弹力蛋白降解和钙在弹力纤维薄层的沉积,从而在单纯收缩期高血压形成中发挥着一定作用.

Objective To investigate the role of matrix metalloproteinase-9（MMP-9） in the formation of isolated systolic hypertension so as to provide a new model of isolated systolic hypertension. Methods Twenty 8-week old male Wistar rats were randomly divided into the model group （n=10） and control group（n=10）. To induce large artery calcification, rats were treated with warfarin and vitamin KI. Eight weeks later, blood pressure and left ventricular pressure were measured by right carotid arterial cannulation. The segments from each aorta were processed for histological analysis by Von Kossa methed. Aortic calcium contents were calculated in each group with atom-spectrum. Elastic fiber structure in aorta was analyzed by elastic fiber staining. MMP-9 expression was determined by immunohistochemistry and Western blot. Results Compared with control group, blood pressures were significantly higher in model group[systolic blood pressure： （151 ±9） vs （113 ±7）mmHg, P〈0.01; diastolic blood pressure： （122± 10） vs （98 ± 8）mmHg, P〈0.05]. The mean left ventricular pressure was not significantly different between the two groups. In model group, the blood pressure fluctuation was associated with morphological change of the aorta, such as extensive arterial medial elastocalcinosis. Compared with control group, calcium content in aorta was significantly higher in model group [（17.9 ± 1.8） vs （5.8 ± 0.6）mg/g, P 〈 0.01]; the elastic lamellae was flatten and lost natural waviness. Western blot analysis showed that MMP-9 protein expression level was significantly higher in model group than in control group. Conclusion Chronic treatment with warfarin and vitamin K1 produce a satisfactory model of isolated systolic hypertension which is identical to the disorder in humans. The elevated expression of MMP-9 enhances the elastin degeneration and calcification of the aortic elastic fibers and plays a role in the formation of isolated systolic hypertension.