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目的探讨小剂量[2μg/(kg.min)]硝酸甘油预处理对大鼠缺血再灌注心肌的保护作用及对caveolin-3表达的影响。方法 24只SD大鼠,完全随机分为3组(n=8):缺血再灌注(I/R)组、小剂量硝酸甘油预处理(PC)组和预处理干预(M)组。采用Langendorff离体心脏灌流方法,制备大鼠离体心脏缺血再灌注模型,离体心脏灌注液为K-H液:I/R组大鼠离体心脏全心停跳30 min,再灌注90 min;PC组在心肌缺血前静脉持续1 h泵入小剂量硝酸甘油[2μg/(kg.min),总量120μg/kg];M组灌注液为含甲基-β环糊精(脂筏清除剂)0.2 mmol/L的K-H液,余处理同PC组。分别观察各组缺血前及再灌注30 min时左室心功能变化情况,并于再灌注末取心肌组织标本,通过ELISA检测心肌组织中cTnI,硝酸还原酶法检测NO变化情况,TUNEL法检测各组心肌细胞凋亡情况、免疫组化方法及PCR方法检测Caveolin-3在各组心肌细胞中的表达变化情况。结果与I/R组比较,PC组左室LVSP、+dp/dtm ax、-dp/dtm ax及心肌组中NO明显升高,cTnI明显降低(P<0.05),心肌细胞凋亡明显减少(P<0.05),免疫组化[光密度值:(0.156 7±0.011 3)、(0.204 0±0.025 8)]及PCR[平均灰度值:(1.167 4±0.105 1)、(1.319 8±0.032 9)]均显示Caveolin-3的表达水平明显增加(P<0.05)。结论小剂量硝酸甘油预处理能明显减轻心肌组织缺血再灌注损伤,其机制可能与影响Caveolin-3的表达有关。
Objective To investigate the protective effect of low dose [2μg / (kg · min)] nitroglycerin on myocardium after ischemia-reperfusion in rats and its effect on the expression of caveolin-3. Methods Totally 24 SD rats were randomly divided into 3 groups (n = 8): ischemia / reperfusion (I / R) group, low dose nitroglycerin pretreatment group (PC) and pretreatment intervention group (M). The isolated rat cardiac perfusion solution was prepared as KH solution by Langendorff perfusion method in vitro. Hearts of isolated hearts in I / R group were stopped for 30 min and then reperfused for 90 min. In the PC group, a small dose of nitroglycerin [2μg / (kg · min), 120μg / kg] was pumped into the anterior vena cava of myocardial ischemia for 1 hour. The perfusion solution of M group was methyl-β-cyclodextrin Agent) 0.2 mmol / L of KH solution, the rest with the PC group. The changes of left ventricular function were observed before ischemia and at 30 min after reperfusion. The myocardial tissue samples were harvested at the end of reperfusion. The levels of cTnI in myocardium were detected by ELISA. The changes of NO were detected by nitrate reductase method. TUNEL assay The apoptosis of myocardial cells in each group, immunohistochemical methods and PCR detection of Caveolin-3 in each group of changes in myocardial cell expression. Results Compared with I / R group, LVSP, + dp / dtm ax, -dp / dtm ax in left ventricle and NO in myocardium were significantly increased, while cTnI was decreased significantly in PC group (P <0.05) Immunohistochemistry [optical density (0.156 7 ± 0.011 3), (0.204 ± 0.025 8)] and PCR [mean gray value: (1.167 4 ± 0.105 1), (1.319 8 ± 0.032) 9)] showed that the expression of Caveolin-3 increased significantly (P <0.05). Conclusion Low-dose nitroglycerin preconditioning can significantly reduce myocardial ischemia-reperfusion injury, and its mechanism may be related to the influence of Caveolin-3 expression.