Cardiomyocyte apoptosis and expression of apoptotic genes in acute myocardial infarction of rats

Objective To determine the changes of cardiomyocyte apoptosis and expression of P53,Fas,Bax and Bcl 2 in a rat model of acute myocardial infarction(AMI).Methods One hundred and nine male Sprague Dawley rats were used in this study.Left anterior descending branch of coronary artery ligation produced extensive AMI in 80 of 101 animals surviving the initial surgery.The 80 survivaing animals were allocated to 10 time points,with 8 rats for each duration of infarction.The remaining eight animals undergoing thoracotomy but not coronary ligation served as sham operation controls.Apoptotic index,P53,Fas,Bax and Bcl 2 expression in myocardium were analyzed semiquantitatively by TUNEL or immunohistochemical means before (sham operation animals) and 1,3,6,12,24 hours and 2,3,5,7,14 days after coronary ligation.Results Only several apoptotic cardiomyocytes were seen in sham operation controls.Immunoreactive positions of P53,Fas and Bcl 2 were also manifested in these control sections.One hour after AMI,the apoptotic index significantly increased,reached a peak 3 days after ligation and then decreased gradually over the remaining 2 weeks.The increase in P53,Fas,Bax and Bcl 2 in the rats of AMI was evident at 6 hours,12 hours,12 hours and 3 hours,respectively;peaked on day 2, day 3,at 24 hours and on day 2 after ligation respectively and then declined gradually to the levels of sham operation controls.Conclusion The current investigation shows that cardio myocyte apoptosis is increased and the expression of P53,Fas,Bax and Bcl 2 in myocardium is also increased in this model,suggesting that they may take part in regulating the cardiomyocyte apoptosis in the rat model of AMI.