| Objective: To evaluate the effect of sevoflurane postconditioning on the protection of myocardial ischemia/reperfusion injury, we observed the hemodynamic change, the change of myocardial enzyme ,the level of plasma TXB2 and 6-keto-PGF1α, myocardial infarct size and myocardial ultrastructure during acute myocardial ischemia reperfusion injury.Methods: Thirty healthy male wistar rats weighing 250～300g, were randomly divided into 3 groups (n=10 for each group): Sham operation group(group S), ischemia-reperfusion group(group I/R), sevoflurane postconditioning group(group Spo). The animals were fasting for 12 hours before operation. All rats were anesthetized by abdominal injection of 3% pentobarbital sodium(45mg/kg), trachealing intubed, machine controlled breathing. The ventilator parameter were set for the tidal volume 15ml/kg (6～10) ml, respiration rate 70～80/min, I/E 2～3:1 .The model of myocardial ischemia reperfusion injury: in open-chest rats the left anterior descending were occluded for 30 minutes and reperfused for 120 minutes. Sham group(group S):Sham-operated rats were placemented of the silk suture under the LAD occlusion, and no other intervention. I/R group:LAD was occluded during 30 min and released for 2h reperfusion placement of the silk suture under the LAD, received no other intervention either before or after LAD occlusion. Sevoflurane postconditioning group (Spo group): administing Sevoflurane (2.5%) were administed for 5 min inhalation 1min prior to reperfusion for 5min. PETCO2, standed ECG lead II,Spo2 and temperature were monitored . PETCO2 was kept at 35～45mmHg , Spo2 was kept above 95%,temperature was kept 37±5℃. HR and MAP were monitored before the artery occluded(T0) , 30 min after the arterial occluded(T1), 5min(T2),10min(T-3),1h(T4) and 2h(T5) after reperfusion . Every group blood samples were taken from carotid for measurement of plasma TXB2 and 6-keto-PGF1αlevel 2h after reperfusion. In ischemia-reperfusion group (I/R group) 5 rats were measured myocardial infarct size, others were observed ultrastructure according electron microscope.Results:1 The age and weight of animals have no significant difference. (P>0.05)2 The results of hemodynamic change Heart rate and mean arterial pressure in group I/R and group Spo decreased significantly compared with that in group S(P<0.05). Heart rate of group Spo at 5min and 10 min after reperfusion decreased significantly compared with that of group I/R (P<0.05). Mean arterial pressure of group Spo at 10 min , 60min,120min increased significantly compared with that of group I/R (P<0.05).3 The level of 6-keto-PGF1αin plasma The level of 6-keto-PGF1αin group I/R and group Spo increased gradually compared with that in group S. There were significant difference among group S , group I/R and group Spo ( p<0.05)4 The level of TXB2 in plasma The level of TXB2 in group I/R and group Spo increased gradually compared with that in group S (p<0.05). There were no significant difference between group I/R and group Spo (p>0.05) .5 The change of TXB2/ 6-keto-PGF1αCompared with that in group S , TXB2/ 6-keto-PGF1αin group I/R and group Spo increased gradually(p>0.05). Compared with that in I/R group, TXB2/ 6-keto-PGF1αin Spo decreased significantly (p<0.05).6 CK-MB in plasma Compared with that in group S, CK-MB in group I/R and group Spo increased significantly (P<0.01).CK-MB in group Spo decreased significantly (P<0.01)7 LDH in plasma Compared with that in group S, LDH in group I/R and group Spo increased significantly (P<0.01). LDH in group Spo decreased significantly compared with that in group I/R (P<0.01).8 Myocardial infarct size Therewere no significant difference of area at risk between group I/R and group Spo .Compared with that of group I/R, the myocardial infarct size of group Spo decreased significantly (p<0.05).9 The results of transmission electron microscope Group S: Myofibril, mitochondrion, mitochondrial cristae are clean. Normal structure of cell is integrity. Group I/R: Endoplasmic reticulum enlarger than group I/R. Nuclelar swelling and disorganization myofibril is disorder part of mitochondrion swelling mitochondrial membrane is not integrity. Group Spo : Endoplasmic reticulum, mitochondrion, and Myofibril are swelling slight.Conclusions:1 sevoflurane postconditioning could effectively reduce infarct size, inhibit leakage of myocardial enzyme, improve cardiac function in experimental rat acute ischemia reperfusion injury model.2 The cardioprotection may due to the highter expression of 6-keto-PGF1α, keeping the balance of TXB2/ 6-keto-PGF1αat certain point.
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