Protective effects of emulsified isoflurane after myocardial ischemia-reperfusion injury and its mechanism in rabbits

Objective: To evaluate the protective effects of 8% emulsified isoflurane after myocardial ischemia-reperfusion injury and its mechanism in rabbits.Methods: Twenty-four male adult New Zealand white rabbits were anesthetized with intravenous injection of 30 mg/kg pentobarbital followed by 5 mg·kg-1·h-1 infusion. All rabbits were subjected to 30 minutes of left anterior de-scending coronary artery (LAD) occlusion and 3 hours of subsequent reperfusion. Before LAD occlusion, the rabbits were randomly allocated into three groups for precondi-tioning treatment (eight for each group). The control group (C group) received intravenously 0.9% NaCl for 30 minutes. The emulsified isoflurane group (EI group) received 8% emulsified isoflurane intravenously till 0.64% end-tidal con-centration for 30 minutes that was followed by a 15-minute washout period. The Intralipid group (IN group) received 30% Intralipid for 30 minutes. The infarcted area, plasma malondialdehyde (MDA) content, superoxide dismutase activity (SOD) and nitrite concentration after 3-hour myo-cardial perfusion were recorded simultaneously.Results: For the myocardial ischemia-reperfusion in-jury animals, the infarcted size in the EI group was signifi-cantly reduced (91.9%±8%) as compared with control group (39%±6%,t=5.19, P<0.01). The plasma SOD activity and nitrite concentration in EI group were significantly higher than those in control group (t=2.82, t=8.46, P<0.05), but MDA content was lower in EI group than that in control group (t=2.56, P<0.05).Conclusions: The results indicate that emulsified isoflurane has a cardioprotection effect against ischemia-reperfusion injury. This beneficial effect of emulsified isoflurane is probably through NO release and consequently by increase in autioxidation of myocardium.