Isoflurane Inhalation After Circulatory Arrest Protects Against Warm Ischemia Reperfusion Injury of the Lungs

Abstract

BACKGROUND: Non-heart-beating donors are expected to ameliorate shortages of donors for organ transplantation. The issue of preventing warm ischemic injury after circulatory arrest must be investigated. In the current study, we investigated whether isoflurane inhalation during warm ischemia could attenuate ischemia reperfusion injury (IRI) of the lung. METHODS: An isolated perfused rat lung model was used. The rats were allocated into four groups: the no ischemia group; the ischemia-1 minimum alveolar concentration (MAC) iso group (ventilation with air and 1.38% isoflurane); the Ischemia-3MAC iso group (ventilation with air and 4.2% isoflurane); and the Ischemia-no treatment group (ventilation with only air). Lungs were subjected to 50 min of ischemia at 37 degrees C. Physiological lung functions were measured after reperfusion in experiment one. Mitochondrial control ratio (RCR), cytochrome-c release from mitochondria, and caspase activities just after warm ischemia were measured in experiment two. RESULTS: Pulmonary functions in the Ischemia-1MAC iso group were significantly greater than those in the Ischemia-no treatment group for experiment one. There were no dose-dependent effects between 1MAC and 3MAC isoflurane. In experiment two, RCR in the Ischemia-1MAC iso group was significantly greater than that in the Ischemia-no treatment group. Cytochrome-c release and caspase-9 activity in the Ischemia-1MAC iso group were significantly decreased compared to those in the Ischemia-no treatment group. CONCLUSIONS: Isoflurane inhalation attenuates warm IRI with the protection of mitochondria. Our results suggest that isoflurane inhalation after circulatory arrest can be a simple and effective method to protect the lung against warm ischemia.