Isoflurane (1.0 MAC) or 20-second postconditioning ischemia significantly reduced myocardial infarct size compared to control (21% and 20% vs 41% of area at risk, respectively; P<0.05).
Does isoflurane reduce infarct size in pentobarbital-anesthetized rabbits subjected to coronary occlusion and reperfusion?
Isoflurane acts during early reperfusion to salvage myocardium from infarction via a PI3K-dependent mechanism in a rabbit model of ischemia-reperfusion.
Absolute Event Rate: 21% vs 41%
p-value: p=<0.05
BACKGROUND: Brief episodes of ischemia during early reperfusion after coronary occlusion reduce the extent of myocardial infarction. Phosphatidylinositol-3-kinase (PI3K) signaling has been implicated in this "postconditioning" phenomenon. The authors tested the hypothesis that isoflurane produces cardioprotection during early reperfusion after myocardial ischemia by a PI3K-dependent mechanism. METHODS: Pentobarbital-anesthetized rabbits (n = 80) subjected to a 30-min coronary occlusion followed by 3 h reperfusion were assigned to receive saline (control), three cycles of postconditioning ischemia (10 or 20 s each), isoflurane (0.5 or 1.0 minimum alveolar concentration), or the PI3K inhibitor wortmannin (0.6 mg/kg, intravenously) or its vehicle dimethyl sulfoxide. Additional groups of rabbits were exposed to combined postconditioning ischemia (10 s) and 0.5 minimum alveolar concentration isoflurane in the presence and absence of wortmannin. Phosphorylation of Akt, a downstream target of PI3K, was assessed by Western blotting. RESULTS: Postconditioning ischemia for 20 s, but not 10 s, reduced infarct size (P < 0.05) (triphenyltetrazolium staining; 20 +/- 3% and 34 +/- 3% of the left ventricular area at risk, respectively) as compared with control (41 +/- 2%). Exposure to 1.0, but not 0.5, minimum alveolar concentration isoflurane decreased infarct size (21 +/- 2% and 43 +/- 3%, respectively). Wortmannin abolished the protective effects of postconditioning (20 s) and 1.0 minimum alveolar concentration isoflurane. Combined postconditioning (10 s) and 0.5 minimum alveolar concentration isoflurane markedly reduced infarct size (17 +/- 5%). This action was also abolished by wortmannin (44 +/- 2%). Isoflurane (1.0 minimum alveolar concentration) increased Akt phosphorylation after ischemia (32 +/- 6%), and this action was blocked by wortmannin. CONCLUSIONS: Isoflurane acts during early reperfusion after prolonged ischemia to salvage myocardium from infarction and reduces the threshold of ischemic postconditioning by activating PI3K.
Chiari et al. (Thu,) conducted a other in Myocardial infarction (n=80). Isoflurane vs. Saline (control) was evaluated on Infarct size (percentage of the left ventricular area at risk) (p=<0.05). Isoflurane (1.0 MAC) or 20-second postconditioning ischemia significantly reduced myocardial infarct size compared to control (21% and 20% vs 41% of area at risk, respectively; P<0.05).