[Changes of apoptosis and Fas gene expression in cardiomyocytes of rats with myocardial reperfusion and the effects of ischemic preconditioning].

OBJECTIVE: To study the changes of apoptosis and Fas gene expression in cardiomyocytes of rats with different duration of reperfusion after myocardial ischemia and the effects of ischemic preconditioning (IPC). METHODS: 108 rats were divided randomly into 6 groups, i.e. sham-operated (observing for 24h in operated control), 30min of ischemia followed by 6h of reperfusion(I(30 min) R(6h)), I(30min)R(12h), I(30min)R(24h), I(30min)R(48h) and IPC. The myocardial cell apoptosis was determined with terminal deoxynucleotidyl transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) method; The protein and mRNA expression of Fas gene were studied with S-P immunohistochemical staining and RT-PCR analysis respectively. RESULTS: Cardiomyocyte apoptosis and the level of Fas gene expression varied with the duration of reperfusion. The apoptotic index (AI) and protein expression index (PEI) of Fas gene in myocytes were highest in rats with I(30min)R(48h) [AI: (38.15 +/- 13.26)%; Fas PEI: (24.77 +/- 12.92)%], but mRNA induction peaked at I(30min)R(24h) (Fas/beta-actin: 0.76 +/- 0.21); PEI of Fas gene correlated significantly with AI of myocytes (r = 0.87, P < 0.01); IPC decreased myocyte apoptosis and down-regulated the protein expression of Fas gene (all P < 0.05). CONCLUSION: The number of apoptotic myocytes and the expression level of Fas gene varied with different duration of myocardial reperfusion. The change of apoptosis and Fas gene expression may be involved in the process of myocardial ischemia reperfusion injury. IPC prevent myocardial injury partly by inhibiting myocyte apoptosis and down-regulating protein expression of Fas gene.