地塞米松在大鼠AMI时对心肌细胞保护作用的实验研究

Experimental investigation of dexamethasone to myocardial cytoprotection on acute myocardial infarction in rats

目的观察地塞米松在大鼠急性心肌梗死(AMI)时对心肌细胞的保护作用。方法将实验动物随机分为假手术组,生理盐水组和地塞米松组(n=8)。结扎大鼠左冠状动脉复制AMI模型。术前分别注入生理盐水及地塞米松,于结扎后2h、4h、8h处死动物,采用免疫组织化学方法检测大鼠心脏缺血区心肌细胞内Bcl-2、Bax的表达情况,免疫抑制法检测血清心肌酶水平。结果在AMI后第4h、8h,地塞米松组Bcl-2蛋白表达的阳性心肌细胞数明显高于生理盐水组(P<0.01),而Bax蛋白表达的阳性心肌细胞数明显低于生理盐水组(P<0.01)。地塞米松组在2h、4h、8h血清CK-MB、α-HBDH含量显著低于生理盐水组(P<0.05)。结论地塞米松可促进AMI时心肌细胞内Bcl-2的表达、抑制Bax的表达,减少心肌酶的漏出,对心肌细胞具有保护作用。

[Objective] To observe the protections of dexamethasone（DM） on the myocardial cells in acute myocardial infarction （AMI） in rats. [Methods] The experimental animals were randomized into three groups, control group, saline group and DM group. And then a rat AMI model was established by left coronary artery ligation. The models were treated with Saline or DM before coronary artery occlusion and then put the rats to death at 2 h, 4 h, 8 h after coronary artery occlusion. The samples of blood and myoeardium were collected for detecting the expression of Bcl-2 and Bax in myocardial cells with immunohistochemistry staining and the changes of MB isoenzym of crea- tine kinase （CK-MB） and α-hydroxybutyrate dehydrogenase in serum with immunosuppression method. [Results] The amount of Bcl-2 protein expression of myocardial cells in DM groups was significantly higher than that in Saline groups at 4 h, 8 h after coronary artery occlusion （P 〈0.01）; However the amount of Bax protein expression in DM groups was lower than that in Saline groups （P 〈0.01）. The levels of CK-MB and α-HBDH had decreased in DM groups compared with those in Saline groups （P 〈0.05） in serum of rats. [Conclusion] DM can promote the expression of Bcl-2 protein and inhibit the expression of Bax protein and decrease the leakage of myocardial enzyme. DM play the role to protect myocardial cells in AMI in rats.