Effect of sevoflurane preconditioning on expression of cyclooxygenase-2 during myocardial ischemia-reperfusion in mice: in vivo and in vitro

Objective To evaluate the effect of sevoflurane preconditioning on expression of cyclooxygenase-2 (COX-2) during myocardial ischemia-reperfusion (I/R) in mice in vivo and in vitro.Methods In the in vivo experiment,54 healthy adult mice,aged 6-8 weeks,weighing 250 g,were randomly divided imo 3 groups (n=18 each):control group (group C),I/R group and sevoflurane preconditioning group (group SP).Myocardial I/R was induced by ligation of the left coronary artery for 30 min followed by reperfusion.In SP group,the mice received 3 episodes of 15 min 2.0％ sevoflurane inhalation at 15 min interval 90 min before I/R.The myocardial specimens were obtained at 6 and 9 h of reperfusion for measurement of COX-2 expression (by Western blot) and caspase-3 activity (by spectmphotometry).Left ventricular end-diastolic pressure (LVEDP) was recorded at 24 h of reperfusion.in the cell experiment,H9C2 cells were randomly divided into 3 groups with 6 dishes in each group:control group (group C),hypoxia-reoxygenation (H/R) group,and sevoflurane preconditioning group (SP group).The cells were exposed to 95％ N2 + 5％ CO2 in an incubator for 14 h followed by reoxygenation with 95％ O2 +5％ CO2 for 3 h.Sevoflurane 2.0 mmol/L was added to the culture medium and the cells underwent 3 episodes of 15 min incubation with 2.0％ sevoflurane at 15 min interval in group SP.H/R was induced 15 min after the end of sevoflurane preconditioning.COX-2 expression was measured at 3 h of reoxygenation by Western blot.Lactic dehydrogenase (LDH) activity in the supernatant and cell lysate was measured by colorimetric method.The release of LDH was caculated.Results In the in vivo experiment,compared with group C,LVEDP and caspase-3 activity were significantly increased and COX-2 expression was up-regulated in groups I/R and SP (P ＜0.01).Compared with group I/R,LVEDP and caspase-3 activity were significantly decreased and COX-2 expression was down-regulated in group SP (P ＜ 0.01).In the cell experiment,compared with group C,COX-2 expression was significantly up-regulated and release of LDH was increased in H/R and SP groups (P ＜ 0.01).Compared with group H/R,COX-2 expression was significantly down-regulated and the release of LDH was decreased in group SP (P ＜ 0.01).Conclusion Sevoflurane preconditioning can reduce myocardial I/R injury through downregulating myocardial COX-2 expression and inhibiting cell apoptosis in mice. Key words: Anesthetics inhalation;  Myocardial reperfusion injury;  Cyclooxygenase 2