Effect Of Thoracic Epidural Block To The Cardiomyocyte Apoptosis In Rats With Coronary Artery Occlusion

BackgroundThe incidence of ischemic heart disease in our country is increasing year by year,and the age is becoming younger and younger.The malignant arrhythmia,heart failure and shock caused by it become terrible killers that threaten people's health.How to better protect ischemic myocardial tissue and relieve the pain of patients with myocardial ischemia and infarction has been a hot topic in clinical medicine research.Excessive activation of sympathetic nerves is closely related to the occurrence of ischemic heart disease.Thoracic epidural block?TEB?can block the sympathetic nerve in the heart area and reduce the myocardial damage caused by sympathetic hyperexcitability.Moreover,TEB may activate the anti-apoptotic pathway and reduce the apoptosis of cardiomyocytes.so as to protect the ischemic myocardial tissue.ObjectivesA rat model of acute myocardial infarction was established by ligation of the left anterior descending coronary artery.By giving the thoracic epidural block on rats before the left coronary artery was ligation,to observe the effect of thoracic epidural block on the apoptosis of myocardial cells and Caspase-3 activity in rats with acute myocardial infarction.Methods1.Research Group Thirty healthy male Wistar rats,8-10 weeks old,were randomly divided into:sham operation group?Sham group?,saline+epidural block of left coronary artery ligation group?CAO group?,ropivacaine epidural anesthesia+left coronary artery ligation group?TEB group?,10 rats in each group.TEB group and CAO group were given0.5%Ropivacaine?0.125ml·kg-1?and the equal amount of saline respectively in the epidural space before the coronary artery was ligation,Sham rats were subjected to left anterior descending coronary artery without ligation,just threading,and give equal saline?0.125mL·kg-1?in the epidural space before threading.2.Hemodynamics and Electrocardiogram?ECG?detection:Use the multi-functional biological acquisition system,connect the ECG to the limbs of rats,monitoring and recording each group rats'heart rate?HR?,mean arterial pressure?MAP?continuously.3.Elisa?enzyme linked immunosorbent assay?method to detect the content of serum troponin I?cTnI?:each rat took arterial blood before opening chest?T₀?,before ligation of the left anterior descending coronary artery?T₁?and 3h after ligature?T₂?,measured cTnI level by ELISA method.4.Western blot method to detect the activity of apoptosis protein Caspase-3 in myocardium:after 3h acute myocardial infarction,the tissue protein was extracted from the infarcted myocardium after cryopreservation,and the Caspase-3 activity of myocardial tissue apoptosis protein was detected.5.Use TUNEL staining to observe the apoptosis of myocardial cells.After left coronary artery ligation 3h,killed the rats,getting the myocardial tissue in ischemic area,making the paraffin sections,according to the TUNEL apoptosis detection kit to observe the apoptosis of cardiomyocytes,and calculated the apoptotic index?AI?.6.Statistical analysis of data:Use SPSS21.0 statistical software analysis,measurement data with mean?x±s?said,the single factor analysis of variance AVONA,comparing mean using t test?P<0.05?for the difference was statistically significant.Results1.After left coronary artery ligation 3h,HR and MAP in group CAO and group TEB were significantly lower than those in Sham group?P<0.05?,but HR and MAP in TEB group were significantly higher than that of CAO group.There was no significant difference between the three groups of rats before the opening of the chest and before coronary artery ligation?P>0.05?.2.After left coronary artery ligation 3h,serum cTnI level in group CAO and group TEB was significantly higher than that in group Sham?P<0.01?,but cTnI level in TEB group was significantly lower than that in CAO group at T₂ time?P<0.05?.There were no significant differences between three groups of rats before the opening of the chest and before coronary artery ligation?P>0.05?.3.After left coronary artery ligation 3h,compared with Sham group,Caspase-3 level in group CAO and TEB increased significantly?P<0.01?,compared with CAO group,Caspase-3 level in group TEB was significantly decreased?P<0.01?.4.After left coronary artery ligation 3h,the apoptosis rate of myocardial cells?AI?in group CAO and TEB was significantly higher than that in Sham operation group?P<0.01?,and the apoptosis rate?AI?of TEB group was significantly lower than that of CAO group?P<0.01?,but it was still higher than that of Sham operation group?P<0.05?.Conclusion1.Thoracic epidural anesthesia can reduce myocardial cell apoptosis after acute myocardial infarction,has certain protective effect on myocardial ischemia or infarction,?2.Its mechanism may be related to excessive inhibition of cardiac sympathetic nerve excitability,reduced catecholamine release,relieve the spasm of coronary artery,increase myocardial oxygen supply on.Moreover,TEB may activate the anti-apoptotic pathway and reduce the apoptosis of cardiomyocytes.