| Objective: Myocardial ischemia reperfusion injury will cause myocardial stunning,arrhythmia,vasomotor dysfunction and other adverse cardiac events.Vitamin C is a weak acidic vitamin,as well as a powerful antioxidant.Previous studies have found that VC could scavenge oxygen free radicals,restrain lipid peroxidation of cell membrane and attenuate the injury of myocardial ultrastructure.However,its effects on the myocardial ischemia reperfusion injury in isolated rat heart remain unclear.Therefore,the present study was designed to elucidate the effect of Vitamin C on the isolated rat hearts during ischemia reperfusion and the related mechanism by compared with the same pH group.Method: Forty Healthy male SD rats,weighing 230-280 g,were randomly divided into four groups: control group,I/R group,VC group,HCL group(pH=5.80,that is the same with VC solution).The isolated rat hearts in control group were perfused 140 min,while they were perfused 20 min for stabilization,30 min for sustained global ischemia and 120 min reperfusion in I/R group.The hearts in VC group and HCl group were given 10 mM VC solution and the same pH HCl solution respectively,and then continued 90 min reperfusion.Model of Langendorff was used in isolated rat heart perfusion,then the indexes including HR,LVEDP,LVSP,±dp/dtmax were recorded at different times.The coronary effluent was collected at baseline and reperfusion 1min,3min,5min,10 min,30min,60 min,90min to measure the LDH activity.After reperfusion,the heart was taken down to measure the myocardial infarct size by TTC staining,observe the cellular morphology by frozen sections after HE staining and detect the expression of related proteins by Western blotting.SPSS 22.0 statistic software was used to analysis and the data was tested by one-way ANOVA.The differences were considered statistically significant when P < 0.05.Results:1 The changes of hemodynamic parametersThere was no significant difference among the hemodynamic parameters at the end of baseline perfused in each group(P>0.05),while they were different at different time during ischemic reperfusion.Compared with the control group,±dp/dtmax in I/R group?VC group and HCL group decreased significantly(P<0.05)and LVEDP increased significantly(P<0.05)at early Stage after ischemia reperfusion.Compared with the I/R group,the indexes in VC group improved significantly(P<0.05).The indexes in HCl group tends to get better,but there is no significant difference(P>0.05).2 The comparisons of myocardial infarct size in each groupCompared with the I/R group(37.92 % ± 1.77 %),the infarct size in VC group(9.04% ± 1.66%)and HCl group(19.58% ± 1.20%)decreased significantly(P<0.05),while it is lesser in VC group(P<0.05).3 The changes of LDH activity in the coronary effluentThe activity of LDH in each group had no significant difference(P>0.05)at the end of the baseline perfused.During reperfusion,the activity of LDH in I/R group?VC group and HCL group increased at different extents,peaked at reperfusion 3min and then decreased gradually.The activity of LDH in I/R group(171.87±47.75 U/L)and HCl group(133.13±36.73 U/L)increased significantly(P < 0.05)compared with the control group(30.02±13.13 U/L),while it decreased significantly in VC group(61.87±30.59 U/L,P<0.05)compared with the I/R group at the end of reperfusion.4 The results of HE staining of myocardial tissueThe myocardial cells in control group arranged in order,with clear boundaries and there was no inflammatory infiltration.The myocardial cells in I/R group arranged in disorder,had different degrees of cell swelling,necrosis and cytolysis.Myocardial fiber ruptured,muscle gap widened obviously and a large number of neutrophil invasion.The myocardial cells in VC group arranged irregularly,partial cells appeared swelling,cytolysis and fragmentation.Muscle gap slightly widened and inflammatory cell infiltrated lightly.The similar phenomenon that myocardial fibers arranged irregularly,cell appeared swelling,cytolysis and fragmentation,muscle gap widened,neutrophil invasion also appeared in HCl group.In conclusion,vitamin C can significantly reduce the ischemia reperfusion injury of the myocardial cells.5 The comparisons of protein expression of cyto-C,Bax,BCl-2,Caspase-9,P-ERK and ERK in each groupCompared with the control group,the expression of cyto-C?Bax?Caspase-9 and P-ERK increased and the expression of BCl-2 decreased(P<0.05),suggesting that mitochondrial damage,apoptotic pathway and ERK signal pathway was activated.Compared with the I/R group,both the VC group and the HCl group had the same pH,the expression of cyto-C?Bax?Caspase-9 and P-ERK in each group decreased and the expression of BCl-2 increased significantly(P<0.05).This showed VC and acidic solution whose pH is same with VC solution could down-regulation of cyto-C?Bax?Caspase-9 protein and up-regulation of BCl-2 protein to protect myocardium,and both of them played their roles through inhibiting ERK signaling pathway.Conclusion:1 Vitamin C postconditioning suppresses ERK signaling pathway to affected on apoptosis which is related with down-regulation of cyto-C?Bax?Caspase-9 protein and up-regulation of BCl-2 protein,improves the ischemia reperfusion injury in isolated rat hearts2 The weak acidity and oxidizability of vitamin C contribute to the protective effect on the ischemia reperfusion injury in isolated rat hearts. |
PDF Full Text Request