贝那普利通过下调心锚重复蛋白改善心肌梗死后心肌重塑

Benazepril improves myocardial remodeling after myocardial infarction by down-regulating cardiac ankyrin repeat protein

目的:探讨贝那普利在改善大鼠心肌梗死后心肌重塑中与心锚重复蛋白(CARP)的相关性。方法:将70只Sprague-Dawley大鼠分为假手术组(20只)、心肌梗死组(25只)和贝那普利组(25只)。术后7 d和28 d,采用随机数字表法每组各时间点分别纳入8只大鼠。心肌梗死组和贝那普利组大鼠按照结扎冠状动脉前降支的方法制作大鼠心肌梗死模型,假手术组麻醉开胸穿线不结扎。贝那普利组采用贝那普利10 mg·kg^(-1)·d^(-1)(溶于5 mL/kg等渗NaCl溶液)灌胃,假手术组和心肌梗死组分别采用等量等渗NaCl溶液灌胃。分别于喂养7 d和28 d后,处死大鼠后取出心脏,测定左心室重量指数(LVWI)和心肌细胞横截面积。采用苏木素-伊红(HE)染色法观察各组大鼠心肌组织病理学特征,最后分别采用酶联免疫吸附测定(ELISA)法和免疫组织化学法检测大鼠血清及心肌细胞中CARP和血管紧张素Ⅱ(AngⅡ)表达水平。结果:HE染色结果显示:术后7 d和28 d,假手术组大鼠心肌结构均完整,细胞排列均整齐,细胞核均位于细胞中央,染色均匀,无肌丝断裂;心肌梗死组大鼠梗死区心肌细胞严重变性和坏死,肌丝排列紊乱,炎症细胞浸润,大量胶原纤维增生,非梗死区心肌细胞代偿性肥大;贝那普利组大鼠心肌细胞病变较轻,炎症细胞浸润较少。心肌梗死组和贝那普利组大鼠28 d时梗死区心肌纤维化均较7 d时更为明显。术后7 d和28 d,3组大鼠LVWI(F=25.111,P<0.001)、心肌细胞横截面积(F=566.062,P<0.001)以及血清和心肌细胞中CARP(F=90.384、23.642,P均<0.001)、AngⅡ(F=97.764、116.133,P均<0.001)水平比较,差异均有统计学意义。进一步两两比较发现,术后28 d,心肌梗死组心肌细胞横截面积以及血清CARP、AngⅡ和心肌细胞中AngⅡ水平均较假手术组和贝那普利组显著升高(P均<0.05)。免疫组织化学法结果显示,CARP和AngⅡ主要在细胞质中表达,假手术组大鼠心肌细胞中黄色和棕色较浅,CARP和AngⅡ阳性表达率较低;心肌梗死组大鼠满布黄色和棕色颗粒,表达较高;贝那普利组阳性表达率介于假手术组和心肌梗死组之间。Pearson相关分析结果显示,术后7 d和28 d,大鼠血清(r=0.796、0.894,P均<0.001)和心肌(r=0.880、0.807,P均<0.001)中CARP与AngⅡ均存在正相关性。结论:心肌梗死后血清及心肌组织中CARP和AngⅡ明显升高,均参与了心肌梗死后心肌重塑,且二者存在正相关性。贝那普利改善心肌梗死后心肌重塑可能与下调CARP有关。

Objective To investigate the relationship between the improvement of myocardial remodeling by Benazepril and the expression of cardiac ankyrin repeat protein(CARP)after myocardial infarction in rats.Methods A total of 70 Sprague-Dawley rats were randomly divided into a sham surgery group(n=20),a myocardial infarction group(n=25)and a Benazepril group(n=25).Eight rats were included at 7 days and 28 days after surgery in each group using random number tables.Rats in the myocardial infarction group and Benazepril group were induced by ligating the anterior descending coronary artery,while rats in the sham surgery group were anesthetized with thoracotomy and threaded without ligation.In the Benazepril group,10 mg·kg^(-1)·d^(-1) Benazepril(dissolved in 5 mL/kg isotonic sodium chloride solution)was used for gavage.Rats in the sham surgery group and myocardial infarction group were treated with 10 mg·kg^(-1)·d^(-1) isotonic sodium chloride solution.After feeding for 7 days and 28 days,the hearts were removed after the rats were sacrificed,and the left ventricular weight index(LVWI)and cardiomyocyte cross-sectional area were determined.The characteristics of myocardial histopathology were observed by hematoxylin-eosin(HE)staining,and the expression levels of CARP and angiotensinⅡ(AngⅡ)in the serum and cardiac myocytes were detected by enzyme-linked immunosorbent assay(ELISA)and immunohistochemistry respectively.Results HE staining showed that at 7 days and 28 days after surgery,the myocardial structures of rats in the sham surgery group were intact,the cells were neatly arranged,and the nuclei were located in the center of the cells,with uniform staining and no myofilament break.In the myocardial infarction group,cardiomyocytes were severely degenerated and necrotic in the infarct area with disordered myofilament arrangement,inflammatory cell infiltration and massive collagen fiber hyperplasia,and cardiomyocytes were compensatorily hypertrophied in the non-infarcted area.Rats in the Benazepril group had milder cardiomyocyte lesions and less inflammatory cell infiltration.Myocardial fibrosis in the infarct zone was more obvious in the myocardial infarction group and Benazepril group at 28 days than at 7 days after surgery.After 7 days and 28 days postoperatively,the levels of LVWI(F=25.111,P<0.001),cardiomyocyte cross-sectional area(F=566.062,P<0.001),and CARP(F=90.384,23.642;both P<0.001)and AngⅡ(F=97.764,116.133;both P<0.001)in serum and cardiomyocytes were compared among the three groups,and the differences were statistically significant.After 28 days after surgery,the levels of cardiomyocyte cross-sectional area,serum CARP and AngⅡ,and cardiomyocyte AngⅡin the myocardial infarction group were significantly higher than those in the sham surgery group and Benazepril group(all P<0.05).The immunohistochemistry showed that CARP and AngⅡwere mainly expressed in the cytoplasm.In the sham surgery group,the myocardial cells were lighter in yellow and brown,and the positive rates of CARP and AngⅡwere lower.Rats in the myocardial infarction group were covered with cloth yellow and brown granules and had higher positive expression.The positive expression rate in the Benazepril group was intermediate between the sham surgery and myocardial infarction groups.In addition,the expression levels of CARP and AngⅡin cardiomyocytes at 7 days in the myocardial infarction group and Benazepril group were higher than those at 28 days.Pearson correlation analysis showed that there were positive correlations between CARP and AngⅡin serum(r=0.796,0.894;both P<0.001)and myocardium(r=0.880,0.807;both P<0.001)at 7 days and 28 days postoperatively.Conclusions After myocardial infarction,CARP and AngⅡare significantly elevated in serum and myocardial tissue and both are involved in its myocardial remodeling,and there is a positive correlation between them.Improvement of myocardial remodeling after myocardial infarction by Benazepril may be related to the down-regulation of CARP.