Effect of sevoflurane preconditioning on pneumocyte apoptosis during pulmonary ischemia-reperfusion injury in mice

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Objective To investigate the effect of sevoflurane (Sev) preconditioning on pneumocyte apoptosis during pulmonary ischemia-reperfusion injury (PIRI) in mice. Methods Sixty C57BL/6J mice were randomly allocated into four groups (n=15 each). In sham operation group (Sham group), left thorax was opened only, hilus of the lung was not clipped, and mechanical ventilation was given for 3.5 h. The left lung of mice received ischemia for 30 min and reperfusion for 3 h in ischemia-reperfusion group (IR group). Mice were inhaled with 2.5% sevoflurane for 30 min, and 15 min later left thorax was opened only, hilus of the lung was not clipped, and mechanical ventilation was given for 3.5 h in Sev group. Mice were inhaled with 2.5% Sev for 30 min and 15 min later the model of PIRI in situ was established with unilateral lung in vivo in Sevo preconditioning + IR group (SIR group). Mice were euthanized after experimental time out, and left lung tissue was excised. Wet lung weight to dry lung weight (W/D) and total lung water content (TLW) were tested. Pathological changes of lung tissue were observed and index of quantitative evaluation for alveolar damage (IQA) was tested by light microscope, and changes of ultrastructure of lung tissue were observed by transmission electron microscope. The expression levels of B-cell lymphoma-2 (bcl-2) and cycteinyl aspirate-specificprotease-3 (Caspase-3) protein were detected by Western blotting, respectively. Apoptosis index (AI) of lung tissue was determined by terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) method. Results Compared to Sham group [(4.32±0.24), (3.32±0.24); (5.71±1.98)%, (4.89±0.99)%], W/D (5.99±0.42), TLW (4.99±0.42); IQA [(40.22±5.39)%] and AI [(35.19±5.94)%] were all notably increased (P<0.05) in IR group. W/D (5.25±0.15), TLW (4.25±0.15), IQA [(14.99±3.56)%] and AI [(16.47±2.69)%] in SIR group were all significantly lower (P<0.05) than those in IR group. Compared to Sham group [(1.16±0.37), (0.96±0.27)], the expression of Caspase-3 protein (2.75±0.76) was significantly increased (P<0.05), while the expression of bcl-2 protein (0.65±0.16) was significantly decreased (P<0.05) in IR group. The expression of Caspase-3 protein (1.46±0.49) in SIR group was significantly lower (P<0.05) than that in IR group (2.75±0.76). The expression of bcl-2 protein (0.78±0.25) in SIR group was significantly higher (P<0.05) than that in IR group (0.65±0.16). Morphological structural injury in lung tissue notably occured in IR group but alleviated in SIR group. Conclusion Sev preconditioning has protective effects on lung against IR injury in mice, which may be related to nhibition of pneumocyte apoptosis. Key words: Sevoflurane; Preconditioning; Apoptosis; Acute lung injury; Ischemia-reperfusion injury; Mouse