Role of protein kinase C in mechanical ventilation-induced lung injury in rats

Abstract

Objective To investigate the role of protein kinase C (PKC) in mechanical ventilation-induced lung injury in rats.Methods Thirty healthy male Wistar rats,weighing 250-300 g,were randomly divided into 5 groups (n =6 each):control group (group C),small tidal volume group (group S),small tidal volume and PKC inhibitor group (group S + P),large tidal volume group (group L),and large tidal volume and PKC inhibitor group (group L + P).VT =42 ml/kg,RR =40 bpm,I∶E =1∶ 2,PEEP =0,FiO2 =21％ in groups L and L + P,while VT=7 ml/kg,RR=40 bpm,I∶E=1∶2,PEEP=0,FiO2 =21％ in groups S and S+P.The rats were only tracheostonized in group C,while the rats were mechanically ventilated for 4 h in the other four groups.PKC inhibitor bisindolylmaleinide Ⅰ 0.12 mg/kg was injected intramuscularly 1 h before anesthesia in groups S + P and L + P.The animals were sacrificed immediacy after tracheotomy in group C,and at 4 h of ventilation in the other four groups and lungs were removed for calculation of wet/dry lung weight ratio (W/D ratio) and for microscopic examination.The expression of occludin was determined in the lung tissues by Western blot.Results Compared with group C,W/D ratio was significantly increased and the expression of occludin was down-regulated in the other four groups (P ＜ 0.05).Compared with group S,W/D ratio was significantly increased and the expression of occludin was down-regulated in group L,and W/D ratio was decreased and the expression of occludin was up-regulated in group S + P (P ＜ 0.01).W/D ratio was significantly lower and the expression of occludin was higher in group L + P than in group L (P ＜ 0.01).The pathological changes were attenuated in groups S + P and L + P as compared with groups S and L.Conclusion PKC is involved in mechanical ventilation-induced lung injury in rats. Key words: Protein kinase C; Respiration, artificial; Respiratory distress syndrome, adult