| Objective:To investigate the influence on lung parenchymal cell apoptosis and the expression of p-Akt, cleaved-caspase3 with sevoflurane preconditioning following cardiopulmonary bypass(CPB)in dogs,and evaluate the role of PI3K/Akt signal path in the effect of sevoflurane preconditioning on alleviating lung injury by cardiopulmonary bypass in dogs Methods: twenty-four dogs were divided randomly into four groups: Sham group(group C, n=6), Ischemic reperfusion group(group I/R, n=6), Sevoflurane preconditioning group(group S, n=6) and PI3 K inhibitor group(group S+W, n=6).All groups were intraperitoneal injected sodium pentobarbital(25 mg·kg-1). Mean arterial pressure(MAP) or mean arterial pressure(MAP) was monitoring by a femoral artery catheter or a femoral vein catheterGroup C was just received mechanical ventilation and median sternotomy; group I/R was used to establish the left lung ischemia-reperfusion injury model; group S was received sevoflurane preconditioning about 30 min at opening left pulmonary arteriovenous; group S+W was accepted the intravenous pumping of PI3 K inhibitor about 10 min before opening left pulmonary arteriovenous and received sevoflurane preconditioning about 30 min at opening left pulmonary arteriovenous. Samples of lung tissue and arterial blood were collected at T1(In front of the CPB), T2(opening the left pulmonary arteriovenous),T3(2 hours after CPB). The arterial blood was used to compute oxygennation index(OI) and respiration index(RI),while the lung tissue were survey the changes of pathology, detected the protein expression of the p-Akt and cleaved-caspase3 by western-blot and estimated apoptosis with terminal-deoxynucleoitidyl transferase-mediated nick end labeling(TUNEL). Results:(1)The change of respiration parameter:There was no significant difference of RI and OI in all groups at T1 time point(P>0.05).Compared with T1 time point, the RI and OI of group C had no significant difference at T2 and T3 time point P>0.05), while the RI of other groups increased,the OI was on the contrary(P<0.05). Compared with T2 time point, the RI of group I/R、group S and group S+W was markedly increased at T3 time point,the OI was decreaed(P<0.05). The RI of group group S、 I/R、and S+W increased at T2 and T3 time point,while the OI declined(P<0.05),compared with group C. Compared with group I/R,the RI of group S was increase,while OI was on the contrary at T3 time point(P<0.05).Compared with group S, the RI of group S+W was increase,while OI was declined at T3 time point(P<0.05).(2) Pathology change of pulmonary tissue: The structures of lung tissue were clear, alveolar septal was not significant expanded;After opening left pulmonary arteriovenous,we found that alveolar septal and capillary of lung tissue were expanded,and a small amount of inflammatory cells was existed in lung tissue.At the end of experiment, The structures of lung tissue appeared disordered, alveolar walls were fractured and lots of inflammatory cells arised in goup I/R, and group S+W;while the pathology change of group S was lighter than other group except for group C.(3) The change of expression of p-Akt,cleaved-caspase3 protein in dogs lung tissue: The expression of p-Akt and cleaved-caspase3 was rare in all groups before thoracotomy(P>0.05).Compared with T1 time point, the expression of p-Akt,cleaved-caspase3 protein in group C had no significant difference at T2 and T3 time points(P>0.05),while the expression of the other group significant increased(P<0.05). Compared with group C, the expression of p-Akt and cleaved-caspase3 increased in the other groups at T2、T3 time points(P<0.05). Compared with group I/R at T3 time point,the expression of p-Akt rised in group S,while the expression of cleaved-caspase3 was on the contrary(P<0.05).There were no dignificant difference in the expresson of these proteins between group I/R and group S+W at T3 time points(P>0.05). Compared with group S at T3 time points, the expresson of p-Akt increased and cleaved-caspase3 declined in group S+W which was administrated PI3 K inhibitor(P<0.05).(4)The change of lung parenchymal cell apoptosis:There was no significant difference of apoptosis index in all groups before thoracotomy(P>0.05). Compared with T1 time point,the apoptotic index of group C had no significant change at T2,T3 time points(P>0.05),while the other groups rised obviously(P<0.05). The apoptotic index of group I/R,S,S+W at T2 time point was higher than T3 time point. Compared with group C(P<0.05), the apoptotic index of rest groups increased at T2,T3 time points(P<0.05). Compared with group I/R, the apoptotic index of group S and groupS+W decreased markedly(P<0.05),while the apoptotic index of group S was lower than group S+W which was used of PI3 K inhibitor(P<0.05). Conclusion: Sevoflurane postconditioning could improve pulmonary fuction and reduce lung parenchymal cell apoptosis,which might be related to the activation of PI3K/Akt signal pathway that could upgrade p-Akt level and downgrade the expression of cleaved-caspase3. |
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