Experimental Study On The Relationship Between Oxidative Stress And Apoptosis Of Cardiomyocyte In Neonatal Rats After Asphyxia

Objective To observe the dynamic changes in the bioactivity of relevant enzymes of Oxidative Stress (SOD, GSH-PX, XOD),the content of the product of lipid hydroperoxide (MDA) and apoptotic index of cardiomyocytes at different time points after asphyxia through establishing the neonatal rats asphyxia model.studying the effect of Oxidative Stress on cardiomyocyte apoptosis in myocardial injury after asphyxia.In ordert o provid reliable laboratory proof for prevention and treatment of the myocardial injury in asphyxia of newborn.Methods 7-day-old newborn SD rats (n=48) were randomly divided into 6 groups with 8 rats in each.first group:normal control group, second group to sixth group were asphyxia groups:after asphyxia 6hour,24hour,48hour,72hour,7day groups.The rats in asphyxia groups were separately put into 55ml container with 0.005Kg of Soda lime, pluging the bottle for half an hour after them to be quiet, then being given oxygen 120minutes and coming back to mother rats keep breast feeding.The rats in asphyxia groups were executed separately after asphyxia 6hour, 24hour,48hour,72hour,7day.The rats in normal control group were separately put into 55ml container with 0.005Kg of Soda lime, opening the bottle for half an hour then coming back to mother rats keep breast feeding after 120minutes, were executed after 6 hours. Each group was taking myocardial tissue samples at the corresponding time pionts, detecting apoptosis of cardiomyocyte and counting positive cells by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate-biotin nick end labeling(TUNEL); the bioactivity of superoxide dismutase (SOD) was measured with the method of xanthinc oxidase;the bioactivity of glutathione peroxidase(GSH-PX)was measured with the method of dithiobisnitrobenzoic acid (DNTB);the content of malondialdehyde(MDA) was measured with the method of thiobarbituric acid(TBA);the bioactivity of xanthine oxidase(XOD) was measured with the method of chemical colorimetry.At last the data were proeessed with SPSS11.5 statistical method.Results (1)The bioactivity of SOD and GSH-PX of after asphyxia 6hour,24hour, 48hour and 72hour were obviously decreased than that of normal control group (P< 0.01),There was no statistical difference between after asphyxia 7day group and normal control group (P>0.05). (2)The content of MDA and the bioactivity of XOD of after asphyxia 6hour,24hour,48hour and 72hour were significantly higher than those of normal control group (P<0.05), There was no statistical difference between after asphyxia 7day group and normal control group (P>0.05). (3) Apoptosis cells of asphyxia groups were sigificantly higher than normal control group (P<0.05), apoptosis cells of after asphyxia 72hour were highest of all,At 7 days apoptosis cells reduced,but were still higher than normal control group.(4)The bioactivity of SOD and GSH-PX have the negative correlation with apoptosis cells,the content of MDA and the bioactivity of XOD have the positive correlation with apoptosis cells.Conclusions Oxidative Stress of cardiac muscular tissue promote cardiomyocyte apoptosis after asphyxia; cardiomyocyte apoptosis is a major form of the myocardial injury after asphyxia; Antioxidant therapy maybe a kind of important method to treat myocardial injury after asphyxia;After asphyxia 7day, Oxidative Stress of cardiac muscular tissue gradually returning to normal,cardiomyocyte apoptosis started to reduce but were still higher than normal control group,which indicated the prevention of myocardial injury should last for 7day after asphyxia,lest aggravate myocardial injury and emerge sequelae.