Sevoflurane Preconditioning On Cardiomyocyte Apoptosis Of Myocardial Ischemia/Reperfusion In Rat In Vivo

Objective1. Through the determination of infarct size and the detection of apoptotic index, we investigate the protection of sevoflurane preconditioning against myocardium ischemia/reperfusion injury in rats in vivo.2. We test the changes of protein Bcl-2 and Caspase-3 before ischemia and after reperfusion by Western immunoblotting analysis in vivo to explore the mechanisma of sevoflurane preconditioning.MethodsExperiment 1:Thirty-two male adult SD rats were set up the model of myocardial ischemic/ reperfusion in vivo and after 30 min baseline period randomly divided into four groups. In CON group (n=4) rats received no ischemic/reperfusion. In I/R group (n=12) rats were experienced 30 min myocardium ischemia and 2 h reperfusion. In SEVO group (n=4) rats were exposed to 1.0 MAC sevoflurane for 30 min followed by memory period of 165 min and in SEVO+I/R group (n=12) rats were exposed to 1.0 MAC sevoflurane before experiencing 30 min myocardium ischemia and 2 h reperfusion. Left ventricle tissue of rats in I/R group and SEVO+I/R group (n=8) was obtained after 2 h reperfusion for myocardial infarct size determination using triphenyl tetrazolium chloride staining. Rats'left ventricle tissue in four groups (n=4) were obtained after 2 h reperfusion or at the corresponding time. The myocardial apoptotic index was evidenced by terminal dUTP deoxynucleotidyl transferase nick end-labeling (TUNEL) analysis.Experiment 2:Another thirty-two male adult SD rats were randomly assigned to four groups which were the same as the experiment before. Left ventricle myocardium samples of all groups were obtained just before ischemia and after reperfusion or at the corresponding time. Bcl-2 and Caspase-3 protein expression were examined by western immunoblotting to detect the changes during the whole experimental period. ResultsExperiment 1:During the baseline period the HR, MAP and RPP had no difference between all groups. As compared with CON group, exposing to sevoflurane for 30min the HR, MAP and RPP in SEVO and SEVO+I/R group were decreased. During reperfusion 1 h and 2 h, the MAP and RPP in I/R group and SEVO+I/R group were decreased (P<0.05). Sevoflurane significantly (P<0.05) reduced infarct size from (52.48±6.04)% (I/R group) to (33.73±5.72)% (P<0.05). After reperfusion exposure to sevoflurane strongly attenuated the myocardial apoptotic index (6.11±1.34)% compared with I/R group (19.16±3.11)%.Experiment 2:Before ischemic: The expression of Bcl-2 protein was up-regulated in SEVO and SEVO+I/R groups as compared to that in the CON group (P<0.05). The expression of protein Caspase-3 had no difference among all groups. After reperfusion: Compared with CON group the Bcl-2 protein expression was down-regulated in I/R group. In SEVO and SEVO+I/R group it was up-regulated. The Caspase-3 protein was increased in I/R group compared with CON group and sevoflurane blocked the changes.Compared with the Bcl-2 protein expression in I/R and SEVO+I/R groups before ischemia, after reperfusion it was down-regulated. The Caspase-3 protein expression in I/R group and SEVO+I/R group after reperfusion was down-regulated compared with it before ischemia. There were no differences of Bcl-2 and Caspase-3 protein in CON and SEVO groups between the two point of before ischemia and after reperfusion. ConclusionSevoflurane preconditioning protected the rat heart against ischemia/reperfusion injury by up-regulation the anti-apoptosis protein Bcl-2 before ischemia. Then it relieved the reduction of Bcl-2 after ischemia/reperfusion and decreased the up-regulation of protein Caspase-3 after reperfusion and ultimately decreased the myocardial apoptosis undergoing ischemia/reperfusion.