Effect Of Benazepril On Connexin 43 Remodelling Reduced By Old Myocardial Infarction

Objective:To observe the effect of benazepril on connexin 43 remodelling in rats with old myocardial infarction and explore its possible mechanism in preventing and curing ventricular arrhythmia.Methods:(1)Making animal model:left anterior descending coronary arteries were ligated to create myocardial infarction model with postoperative recovery lasting 4 weeks;(2)24 rats were randomly divided into 3 groups:control group(n=8),old myocardial infarction group (GroupⅠ,n=8),old myocardial infarction combining with benazepril group(GroupⅡ,n=8); (3)16 rats were randomly divided into 2 groups:control group(n=8)and benazepril group(n=8); (4)the pathology of myocardial cell were observed by hematoxylin and eosin(HE)stain with microscopy;(5)Distributions of Cx43 in myocardial infarction zone,boundary zone and non-ischemic zone were observed using immunocytochemical method,meanwhile,distributions density of Cx43 in myocardial tissue was determined by semiquantitative analysis.Results:1.Rat mortalities were respectively 11%,12.87%,7.92%and 4.95%in operation,in 72h,1-2w,2-3w after operation.the survival rate beyond 3 weeks reached 63.37%.Cavitas thoracis was opened after 4 weeks,the infarction zone was substituted by scar tissue,which resulted in its growing thin,pale.the non-infarction zone shew to myocardial hypertrophy,the left ventricular chamber distension,which demonstrated myocardium pathologic and morphologic change exist in MI.2.HE staining revealed that cardiac muscle cell structure of OMI rats shew up visible change.MI zone developed obvious cardiac muscle necrosis,oboslete cicatrisation,a great number of inflammatory cell infiltration,fibroblast proliferation.In MI marginal zone, myocardial cell structure is normal in the main,but there are inflammatory cell infiltration;in MI distal end,myocardial cell structure is normal.3.immunocytochemical staining revealed that Cx43 was not found in the necrotic zone.In GroupⅠ,contents of Cx43 in the boundary zone were significantly lower than those in control group respectively(p＜0.01),and the distributions of Cx43 was inhomogeneous.In GroupⅡ,the changes Cx43 were similar to those in GroupⅠcompared with control group(p＜0.01),but the levels of Cx43 increased significantly than those in GroupⅠrespectively(p＜0.01),and the alleviation of inhomogeneity in the Cx43 distribution was observed as well.In non-ischemic zones,there were no significant changes in Cx43 density or distributiong in GroupⅠand in GroupⅡcompared with control group(p＞0.05).In benazepril group,contents of Cx43 in lateral wall,posterior wall of cardiac muscle were significantly higher than those in control group (p＜0.01).Conclusion:1.There were markedly inhomogeneities in distribution and density of Cx43 in old myocardial infarction,especially in the boundary zone.2.Benazepril can effectively alleviate Cx43 remodelling induced by old myocardial infarcttion.3.Benazepril can increase contents of Cx43 in normal ventricular myocardium.