Effect of emulsified isoflurane post-conditioning on mitochondrial function during lung ischemia-reperfusion in rats: an in vitro experiment

Abstract

Objective To evaluate the effect of emulsified isoflurane post-conditioning on the mitochondrial function during lung ischemia-reperfusion (I/R) in rats in an in vitro experiment. Methods Twenty-four SPF healthy male Sprague-Dawley rats, weighing 250-300 g, were used in the study.After the animals were anesthetized, the lungs were removed, connected to the perfusion system and then divided into 4 groups (n=6 each) using a random number table: control group (group C), group I/R, emulsified isoflurane post-conditioning group (group EI) and intralipid post-conditioning group (group IL). After 20 min of equilibration, the lungs were continuously perfused for 105 min in group C, and the lungs were subjected to 45 min ischemia followed by 60 min reperfusion to establish the model of lung I/R injury in the other three groups.During the reperfusion period, the common perfusate was used in group I/R, the perfusate containing 1.68 mmol/L emulsified isoflurane was used in group EI, and the equal volume of perfusate containing 30% intralipid was used in group IL.At the end of the equilibration (T0), immediately after beginning of reperfusion (T1) and at 30 and 60 min of reperfusion (T2, 3), the arterial oxygen partial pressure (PaO2), airway resistance, pulmonary compliance and tidal volume (VT) were recorded.The right upper lobe of the lung was removed at T3 for determination of wet to dry weight ratio (W/D ratio). The right middle lobe of the lung was removed at T3 for pathologic examination with light microscope.The contents of reactive oxygen species (ROS), NAD+ and ATP in lung tissues were detected. Results Compared with group C, the PaO2, pulmonary compliance and VT were significantly decreased, and the airway resistance was increased at T1-3, and the W/D ratio and ROS content were increased, and NAD+ and ATP contents were decreased at T3 in I/R, EI and IL groups (P<0.05). Compared with I/R and IL groups, the PaO2, pulmonary compliance and VT were significantly increased, and the airway resistance was decreased at T2, 3, and the W/D ratio and ROS content were decreased, and NAD+ and ATP contents were increased at T3 in group EI (P<0.05). The pathologic changes of lungs were significantly attenuated in group EI as compared with group I/R. Conclusion The mechanism by which emulsified isoflurane post-conditioning attenuates lung I/R injury is related to decrease in mitochondrial dysfunction in rats in an in vitro experiment. Key words: Isoflurane; Fat emulsions, intravenous; Reperfusion injury; Lung; Mitochondrial; Ischemia post-conditioning