硝酸甘油预处理的心肌保护作用及对Caveolin-3表达的影响

Nitroglycerin preconditioning protects heart ischemia-reperfusion injury in rats by improving Caveolin-3 expression

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 effects of pretreatment of nitroglycerin at a small dosage [2 μg/（kg·min）] on the hemodynamics of the rats with heart ischemia-reperfusion injury,and explore the mechanism of nitroglycerin preconditioning for myocardial protection on the rats.Methods Twenty-four rats were completely randomly assigned to 3 different groups,ischemia-reperfusion（I/R） group,nitroglycerin preconditioning（PC） group and M-β-CD treatment（M） group.The isolated hearts were passively perfused on a Langendorff apparatus with 37 ℃ Kerbs-Henseleit buffer（KHB） saturated with mixture gas,which containing 95%O2-5%CO2.The I/R group was undergone 30 min ischemia and then 90 min reperfusion.The PC group was continuous pumping small dosage of nitroglycerin in 1 h before the hearts underwent the ischemia.The M group was passively perfused with K-H buffer containing 0.2 mmol/L M-β-CD.ELISA was used to measure the changes of left ventricle function and the cardiac troponin I（cTnI）,and nitrate reductase method was used to measure the nitric oxide concentration in the left ventricular muscles homogenate.The apoptosis of the cardiac myocytes was tested with TUNEL,and the expression of caveolin-3 in the different cardiac myocytes was determined with immunohistochemisty and PCR.Results Compared with the I/R group,the LVSP,＋dp/dtmax,-dp/dtmax and NO concentration were significant higher（P0.05） and while the cTnI,apoptosis of the cardiac myocytes were significant lower in PC group（P0.05）.Immunohistochemisty and PCR showed that the expression of Caveolin-3 were significant higher in the PC group than in I/R group（0.204 0±0.025 8 vs 0.156 7±0.011 3,1.319 8±0.032 9 vs 1.167 4±0.105 1,P0.05）.Conclusion Continuous pumping of nitroglycerin at a small dosage in 1 h before ischemia exerts protective effct on myocardiocytes through activating Caveolin-3.