达格列净预处理对心肌缺血再灌注损伤模型兔血清hs-cTnT、心肌结构及细胞凋亡的影响

Effect of Dapagliflozin Pretreatment on Serum High-sensitive Cardiac Troponin T,Myocardial Structure and Apoptosis of Myocardial Ischemia-reperfusion Injury Model Rabbits

目的探索达格列净预处理对心肌缺血再灌注损伤(MIRI)模型兔血清高敏心肌肌钙蛋白T(hs-cTnT)、心肌结构及细胞凋亡的影响。方法18只雄性成年新西兰大白兔依据随机数字表法分为假手术组、模型组和达格列净组,每组6只。假手术组:在兔的左前降支下方只穿线,不结扎;模型组:用缝合线穿绕兔心脏左前降支中、上1/3交界处并在此放置一束线后一起结扎,结扎40 min后再灌注120 min;达格列净组:结扎前20 min经兔耳缘静脉给予达格列净0.5 mg/kg。三组分别于结扎前、结扎40 min、再灌注120 min时留取血标本检测血清hs-cTnT水平;取缺血区心肌组织,观察各组心肌组织病理学变化;末端脱氧核苷酸转移酶介导的原位缺口末端标记(TUNEL)法观察细胞凋亡情况,通过阳性细胞计数评价凋亡情况。结果hs-cTnT不同时点间、组间的主效应差异有统计学意义(P<0.01),组间和时点间存在交互作用(P<0.01);结扎后40 min和再灌注120 min,模型组与达格列净组血清hs-cTnT均显著高于假手术组(均P<0.01),但达格列净组血清hs-cTnT明显低于模型组(P<0.01);模型组与达格列净组血清hs-cTnT均随着缺血及再灌注时间延长而增加(P<0.01)。与假手术组相比,模型组的心肌细胞形态改变和坏死严重;达格列净组的心肌细胞也有形态改变和坏死,但病变程度明显轻于模型组。假手术组、模型组、达格列净组凋亡指数分别为(10.0±0.9)%、(42.4±1.5)%、(28.6±1.2)%,与假手术组相比,模型组与达格列净组凋亡指数均增加(P<0.01),而与模型组相比,达格列净组凋亡指数降低(P<0.01)。结论达格列净预处理对缺血再灌注损伤心肌具有保护作用,其作用机制可能与减少心肌酶释放和心肌细胞凋亡有关。

Objective To explore the effects of dapagliflozin pretreatment on serum high-sensitive cardiac troponin T(hs-cTnT),myocardial structure and cell apoptosis of myocardial ischemia-reperfusion injury(MIRI)model rabbits.Methods Eighteen male adult New Zealand rabbits were randomly divided into a sham-operated group,a model group,and a dapagliflozin group,with 6 rabbits in each group.In the sham-operated group,only a suture was threaded under the left anterior descending branch of the rabbit without ligation;in the model group,a suture was threaded around the upper middle third of the left anterior descending branch of the rabbit′s heart and a bundle of sutures was placed there and then ligated together,and the rabbit was reperfused for 120 min after ligation for 40 min;in the dapagliflozin group,dapagliflozin 0.5 mg/kg was given through the ear margin vein 20 min before ligation.The levels of hs-cTnT of the three groups were measured before ligation,40 min after ligation and 120 min after reperfusion;myocardial tissue was taken from the ischemic area to observe the histopathological changes in the myocardium of each group;terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)method was adopted to observe apoptosis and apoptosis levels were assessed by positive cell counts.Results The main effect difference of hs-cTnT at different time points and between groups was statistically significant(P<0.01),and there was interaction between groups and time points(P<0.01).After ligation for 40 min and reperfusion for 120 min,the serum hs-cTnT of the model group and dapagliflozin group was significantly higher than that of the sham-operated group(all P<0.01),but the serum hs-cTnT of dapagliflozin group was significantly lower than that of the model group(P<0.01).The serum hs-cTnT of the model group and dapagliflozin group increased with the prolonging of ischemia and reperfusion time(P<0.01).The model group had severe morphological alterations and necrosis of cardiomyocytes compared to the sham-operated group.The myocardial cells in the dapagliflozin group also showed morphological changes and necrosis,but the extent of lesions was significantly less than that in the model group.The apoptosis indexes of the sham-operated group,model group and dapagliflozin group were(10.0±0.9)%,(42.4±1.5)%,(28.6±1.2)%,respectively.Compared with the sham-operated group,the apoptosis index of the model group and the dapagliflozin group was increased(P<0.01),while the apoptosis index of the dapagliflozin group was lower than the model group(P<0.01).Conclusion Dapagliflozin pretreatment has a protective effect on ischemia-reperfusion injured myocardium.The mechanism may be related to the decrease of myocardial enzyme release and myocardial cell apoptosis.