Effects of xenon and isoflurane on apoptosis and inflammation in a porcine myocardial infarction model.

Volatile anaesthetics can reduce the infarction size in myocardial tissue when administered before and during experimentally induced ischaemia. The aim of this study was to investigate whether xenon is beneficial compared to isoflurane in limiting myocardial tissue apoptosis and inflammation induced by experimental ischaemia-reperfusion injury in a porcine right ventricular infarction model. Twenty-one animals used for this study randomly received isoflurane, xenon or thiopental, (n=6-8 per group). Myocardial infarction was induced for 90min, followed by reperfusion for 120min. Tissues from the left and right ventricles were removed from the sites of infarction, reperfusion and remote areas, and processed for immunohistochemistry. Apoptosis (caspase-3 staining) and neutrophilic infiltration (naphthol AS-D chloroacetate-specific esterase) were assessed and evaluated. Statistical analysis was performed using an ANOVA of repeated measures. Density of apoptotic cells were higher in tissues from animals that were anesthetized with xenon. This effect was significant in comparison to isoflurane (p=0.0177). Neutrophilic infiltration was significantly higher in the right compared to the left ventricle (p<0.001), whereas no significant differences in the number of granulocytes based on the anaesthetic regime or the different tissue areas were found. We conclude that xenon, in the early phase of ischaemia and reperfusion, induces a significant increase in apoptosis compared to isoflurane. Therefore, clinical use of this anaesthetic in cardiocompromised patients should be taken with care until more long-term studies have been carried out. The increased neutrophilic infiltration in the right vs. the left ventricle indicates the right ventricle being more susceptible to ischaemia-reperfusion injury.