Hypoxia-reoxygenation induced apoptosis and its signal regulation in human hypertrophic cardiomyocytes

Objective: To investigate the changes of apoptosis and its signal regulation in human hypertrophic cardiomyocytes induced by hypoxia and reoxygenation.Methods: Adult human hypertrophic cardiomyocytes were cultured and digested in trypsin and collagenase.The apoptotic cells were induced by hypoxia-reoxygenation and their rate was evaluated by a modified TUNEL method.The changes in the Bcl-2,Bax,Caspase 3,cytochrome C and Phosphotyrosine proteins were detected by immunocytochemistry(ICC),those in Bcl-2 mRNA,Caspase 3 mRNA,and Akt1 mRNA by ISH Detection Kit,and the results were statistically analyzed by SPSS 10.0.Results: The apoptosis rate of cardiomyocytes induced by 24 h hypoxia-4 h reoxygenation(H/R) was(17.50± 0.67)% vs(2.88±0.27)% in the control group;the average A values of the apoptotic signals were(0.189±0.006) in Bcl-2,(0.240 ±0.002) in Bax,(0.230±0.002) in Caspase 3,(0.225±0.003) in Cytochrome C,and(0.186±0.005) in Phosphotyrosine proteins,as compared with(0.238±0.004),(0.218±0.004),(0.202±0.004),(0.191±0.009) and(0.154±0.003) respectively in the control group;and the expression of bcl-2 mRNA was(0.300±0.003),Caspase 3 mRNA(0.307±0.004) and Akt1 mRNA(0.274±0.007) in comparison with(0.360±0.001),(0.271±0.002) and(0.301±0.008) in the controls,all with statistically significant differences between the two groups(P0.01).Conclusion: Hypoxia-reoxygenation can significantly increase the apoptosis rate of hypertrophic cardiomyocytes,down-regulate the expressions of the Bcl-2 protein,Bcl-2 mRNA and Akt1 mRNA,and up-regulate the expressions of Bax,Caspase 3,Cytochrome C and Phosphotyrosine proteins and Caspase 3 mRNA in cardiomyocytes.