The Effect Of Adenosine On Ischemia-reperfusion Myocardial Cx43 In Rats And The Relation Between Reperfusion Ventricular Arrhythmias And Adenosine

Objective: this study is to observe the effects of adenosine preconditioning and postconditioningon ventricular arrhythmias caused by ischemia-reperfusion, and to observe the effect ofadenosine on the expression and distribution of myocardial Cx43, and to preliminary study theregulation mechanism of adenosine on Cx43.Methods: 32 cases (male Wistar rats) were randomly allocated into 4 groups and each group had8 rats. Ischemia-reperfusion model in rats in vivo were established and a leadⅡECG wasrecorded. The left anterior descending was ligated and it resulted in left ventricular myocardialischemia. When the ligature was loosened, it meant that the reperfusion is starting. All the rats inexperiment were needed to open the chests. sham operation group（n=8）:The rats wereanesthetized with urethane for 150 minutes without ligating the left anterior descending;ischemia-reperfusion group（n=8）:The rats stayed in ischemia for 30 minutes and thenreperfusion for 2 hours. There was no other special treatment; adenosine preconditioning group（n=8）:The rats were given adenosine for 5 minutes before ischemia, and the adenosine wasgiven through the femoral vein with micro-injection pump by 305μg/(kg·min).Other processingwas the same as the I/R group;adenosine postconditioning group（n=8）:The rats were givenadenosine for 5 minutes before reperfusion, and the adenosine was given through the femoralvein with micro-injection pump by 305μg/(kg·min).Other processing was the same as the I/Rgroup.The cellular morph after hematoxylin-eosin stain processing were observed and analyzedby light microscope; expression of Cx43 protein was observed by immunohistochemicaltechnique. Observe the ventricular arrhythmias at the first 30min of reperfusion and calculate theventricular arrhythmias score in rats in each group; The cell apoptosis of each group wasobserved by Tunel method.Result：1. To observe HE staining results by light microscope: Compared with the shamoperation group, the degree of myocardial injury of I/R group were much heavier; Comparedwith the I/R group, the degree of myocardial injury of adenosine preconditioning group andadenosine postconditioning group were much litter. 2. The results of Cx43 immunohistochemicalstaining and ventricular arrhythmia score: Compared with the sham operated group rats, Cx43expression level in I/R group was significantly reduced (p<0.05) and the distribution was in greatdisorder, while ventricular arrhythmia score in I/R group was obviously increased(p<0.05). But compared with the I/R group, Cx43 expression level in adenosine preconditioning group andadenosine postconditioning group were significantly increased (p<0.05),and the inhomogeneityin Cx43 distribution were decreased,while ventricular arrhythmia score in adenosinepreconditioning group and postconditioning group were all decreased(p<0.05). 3. Measure thecardiomyocyte apoptosis by Tunel method: the rate of cardiomyocyte apoptosis of the I/R groupwere higher than the sham group (p<0.05), and the rate of cardiomyocyte apoptosis of adenosinepreconditioning group and adenosine postconditioning group were lower than the I/R group（p<0.05）;there are no difference between adenosine preconditioning group and adenosinepostconditioning group (p>0.05).Conclusion: Adenosine can reduce the incidence of reperfusion ventricular arrhythmias, and thiseffect may due to inhibiting the degradation of Cx43 and improving its distribution.