Emulsified isoflurane produces cardiac protection after ischemia-reperfusion injury in rabbits

BACKGROUND: In this study, we examined the cardioprotective effects of parental emulsified isoflurane compared with inhaled isoflurane. METHODS: Thirty-two rabbits were subjected to 30 min of myocardial ischemia induced by temporary ligation of the left anterior descending coronary artery followed by 3 h of reperfusion. Before left anterior descending coronary artery occlusion, the rabbits were randomly allocated into one of four groups (eight for each group): group C, no ischemia preconditioning treatment; group IS, inhaled isoflurane 1.1% end-tidal; group El, a continuous infusion of 8% emulsified isoflurane to an end-fidal concentration of 0.64%; and group IN, a continuous infusion of 30% Intralipid(R) started 30 min. Treatments were started 30 min before ischemia followed by a 15 min washout period for isoflurane groups. Myocardial infarct volume, lactate dehydrogenase, and creatine kinase levels were measured and changes in mitochondrial ultrastructure assessed after 3 h myocardial reperfusion. RESULTS: Myocardial infarct size 3 h after reperfusion was lower in groups IS and El compared with groups C and IN (20% +/- 8%,18% +/- 8%,39% +/- 6%, and 34% +/- 9%, respectively, P < 0.01). There were no differences in myocardial infarct size between groups IS and El or between groups C and IN. Plasma lactate dehydrogenase and creatine kinase levels were lower in group IS (456 +/- 58 U/L and 1725 +/- 230 U/L) and group El (451 +/- 54 U/L and 1686 +/- 444 U/L) 3 h after myocardial reperfusion compared with groups C (676 +/- 82 U/L and 2373 +/- 529 U/L; P < 0.01). Mitochondrial ultrastructure changes were less pronounced in groups IS and El compared with group C. CONCLUSIONS: Our results indicate that, in rabbits, IV emulsified isoflurane provides similar myocardial protection against ischemia-reperfusion injury as inhaled isoflurane.