Effect Of Ischemic Preconditioning Combined With Pyrrolidine Dithiocarbamate On Apoptosis Of Lung Parenchymatous Cells And The Expression Of Nuclear Factor-κb

Objective: Through observing the effect of ischemic preconditioning (IPC) combined with pyrrolidine dithiocarbamate ( PDTC ) on the expression of nuclear factor-Кb (NF-Кb) , the apoptosis of lung parenchymatous cells and the lung function, to investigate the protective mechanism of ischemic preconditioning combined with pyrrolidine dithiocarbamate (PDTC) to the lung injury induced by ischemic reperfusion (IR).Methods: 18 healthy new-zealand rabbits were randomly divided into 3 groups (6 for each group): ischemic reperfusion group (group IR),ischemic preconditioning group (group IPC) and ischemic preconditioning combined with pyrrolidine dithiocarbamata group (group IPC+PDTC). In Group IR: hilum of left lung was occluded for 60min and then realeased for 120 min after anesthesia stabled. In Group IPC: IPC was achieved by first two 10-min cycles of ischemic and each was followed by a 10-min reperfusion and then repeated the procedures of group IR;In Group IPC+PDTC: 15 minutes before IPC, PDTC 10mg/kg was given by intravenous injection and then followed the procedure as in group IPC. Arterial blood was sampled at following time point: after anesthesia stabled immediately,60 min after the ischemia immediately,and 30 min ,60 min and 120 min after the reperfusion. Blood gas analysis was done for all the samples and pulmonary ventialtion function was then calculated from the result of blood gas analysis. After operation, the left lung tissue was sampled for apoptotic cells and the expression of NF-Кb check, histopathology of lung tissue examination and wet/dry ratio examination.Results: Blood gas analysis showed there were no significant difference among three groups at the time point of anesthesia stabled immediately(P>0.05). Oxygenation index was significantly higher and alveolar-arterial oxygen gradient (A-aO2 ) was significantly lower in group IPC and group IPC+PDTC than group IR at the time point of 60 min after the ischemia immediately , 30 min,60 min and 120 min after the ischemic reperfusion (P<0.05,P<0.05,P<0.01,P<0.01)and there was also significant difference between group IPC and group IPC+PDTC (P<0.05,P<0.05,P<0.01) at three times point of after the ischemic reperfusion. After operation, wet/dry ratio of lung tissue showed group in IR, IPC, IPC+PDTC :5.2583±0.1365,3.9235±0.1324,3.3065±0.1485,IPC and group IPC+PDTC was significantly lower than group IR (P < 0.01). Compared with group IPC, group IPC+PDTC was significantly lower (P< 0.05).The rate of lung parenchyma cells apoptosis is (22.50±1.24)% in group IR , (12.69±0.56)% in group IPC and (7.79±0.47)% in group IPC+PDTC . Compared group IR with group IPC and group IPC+PDTC, the difference was significant (P < 0.01), while group IPC+PDTC was significant lower than group IPC (P<0.05).The expression of NF-Кbp65 protein measured by immunohistochemistry was showed as followes: the frequency of lung parenchyma cells positive with NF-Кbp65 is (55.2±0.55)%in group IR, (43.3±0.33)% in group IPC and (33.2±0.48)% in group IPC+PDTC. The expression of NF-Кbp65 protein was significantly reduced in group IPC and group IPC+PDTC compared with group IR (P<0.01), while there was also significant difference between group IPC and group IPC+IPDC (P<0.05). The histopathology of lung tissue in group IR showed large ammountacumulation of neutrophil and lymphocyte, congestion of blood capillary, edema of alveolus , collapse of alveolar and abnormal construction of alveolar cell; but in group IPC just showed a few neutrophil and lymphocyte accumulation, a small quantity of congestion in several blood capillary and minor edema of alveolus; The degree of lung tissue injury is slight in group IPC+PDTC.Conclusion: It is suggested that lung ischemic preconditioning can reduce lung ischemia-reperfusion injury and ischemic preconditioning combined with PDTC may be has synergy effect. The protective mechanism of ischemic preconditioning combined with pyrrolidine dithiocarbamata may be due to reduce the apoptosis of human lung cells and the release of inflammatory cytokines by inhibiting the expression of NF-Кb protein .