| ObjectivesA pig model of acute lung injury following intestinal ischemia reperfusion was set up. We investigated the protective effects and probable mechanism of propofol, aiming to provide experiment evidences during perioperative period about using propofol to prevent remote organs from injury following ischemia reperfusion.MethodsTwenty four pigs were randomly divided into three groups (n=8each): sham group(S);ischemia reperfusion group(I/R); propofol group(I/R+P). Each animal was connected to a ventilator for mechanical ventilation after anesthesia and tracheal intubation. GroupI/R: intestinal I/R was produced by clamping super mesenteric artery(SMA) for2hours and declamping SMA for4hours. GroupI/R+P:a dose of10mg/kg/h propofol was continuously infused before10minutes of reperfusion until the end of operation, other procedures were the same with group I/R. Group S:the SMA was exposed and isolated without clamping, other procedures were the same with groupI/R.All animals were sacrificed at the end of reperfusion. Lung static compliance and airway resistance were recorded at four time points:15minutes after tracheal intubation(TO),2hours after ischemia(T1),2and4hours reperfusion(T2and T3). Simultaneously, artery blood samples in this four time points were collected for the determination of malondialdehyde, the activity of superoxide dismutase and myeloperoxidase. Blood samples in T4were extracted to do blood gas analysis and obtain PH?PaO2, and then DA-aO2was calculated. The determination of hydrogen sulfide in blood plasma was also analyzed. Beside, the level of malondialdehyde, the activity of myeloperoxidase, superoxide dismutase and cystathionine-gamma-lyase of the lung were analyzed. Finally, bronchoalveolar lavage fluid was collected. The permeability index and the Wet/Dry Ratio of the lung were analyzed. Histopathological changes was observed under optical microscope after HE staining.Results1. The structure of lung tissue observed by optical microscopy was normal in group S. There was massive infiltration of neutropHils among alveolar, interstitial tissue and capillary, also, serious consolidation of lung tissue in group I/R. Pathological changes in group I/R+P were lightened significantly compared with group I/R, no obvious infiltration of neutropHils was found in this group. 2. The Wet/Dry Ratio and lung permeability index in group I/R were higher than group S,(P<0.01), this two parameters were lower in group I/R+P than group I/R,(P<0.05or P<0.01respectively).3. PaO2and PH in group I/R were significantly lower than that of group S and group I/R+P (P<0.01).remarkable rise could be found about DA-aO2in group I/R (P<0.01). It showed increase of Pa02and PH and significant decline of DA-a02in I/R+P compared wi group th group I/R(P<0.01).4. Static lung compliance and airway resistance showed no significant difference in group S. Static lung compliance reduced and airway resistance increased gradually with time went by in group I/R, there were significant differences in T3compared with group S(P<0.01). Static lung compliance and airway resistance also showed gradual decline and increase in group I/R+P, but the two parameters was higher and lower respectively than that of group I/R in T3(P<0.05or P<0.01respectively)5. The activity of SOD of lung was significantly lower in group I/R compared with group S(P<0.01), the content of MDA, the activity of MPO were significantly higher than that of group S(P<0.01). It showed increase of the activity of SOD, decline of the content of MDA and decrease of the activity of MPO in group I/R+P than that of group I/R(P<0.05). But the activity of SOD was still lower than that of group S(P<0.01), the content of MDA and the activity of MPO were also higher than that of group S(P <0.05).6. The activity of plasma SOD was gradually declined in each time points, and it showed differences in each time points compared with group S which had no obvious changes at the same time points(P<0.05). The content of MDA and activity of SOD rose continuously and also displayed differences compared group S (P<0.01or P<0.05respectively). The activity of plasma SOD showed decline gradually in group I/R, but it was higher than that of group I/R at the same time points(P<0.01), and the content of MDA and activity of SOD were lower than that of group I/R at the same time points(P<0.01or P<0.05respectively).7. There were no significant differences about the content of H2S in plasma and the activity of CSE of lung between group I/R and group I/R+P (P>0.05), but this two parameters in group I/R and group I/R+P were all higher than group S (P<0.01). Conclusion This study makes a pig model of superior mesenteric artery ischemia reperfusion and finds it can lead to acute lung injury. Propofol administrated before reperfusion has protective effects on the lung injury. |
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