Abstract: Objective Cardio-cerebrovascular disease is a high incident disease in the world，the research of which depends on the establishment of animal models.The purpose of this study was to observe the myocardial changes with time in rabbit congestive heart failure models（CHF），as well as its relationship to Nitric Oxide（NO）。Method Twenty-four rabbits were randomly assigned into three groups with eight rabbits in each one：normal group，model 24h group and model 7d group The model of CHF with volume overload was set up via catheterization，and then the rabbits were executed after 24h and 7d respectively，whose myocardial tissue was used for light microscopic examination.Serum NO was measured using NO assay kit，and myocardial apoptosis was detected by flow cytometry.Caspase-3 expression was determined by Western Blot analysis.Results（1）The structures of myocardial cells in normal group were intact，and there were no defects.The myocardial injury was found in the group of CHF model after 24 h and 7d，while the injury in the 7d group was more extensive and serious.（2）The contents of serum NO increased significantly in model 24h group （3.33±1.30 μmol/L）compared with the normal group（2.09±0.22 μmol/L）（P＜0.05），and decreased a little in model 7d group（2.81±0.77 μmol/L）。（3） The apoptosis rate were（3.72±1.92%），（7.62±1.70%）and（10.73±2.26%）respectively，which is going up as time goes on.（4）The results of Western Blot analysis showed that there was almost no expression of the active form of Caspase-3 in the normal group.The level of Caspase-3 expression was significant in the 24h group and 7d group，while the latter decreased somewhat.Conclusion As time went on，the apoptosis rate increased and myocardial injury aggravated，and the main function of NO is anti-apoptotic in the model。

Key words: Myocardial tissue, Congestive heart failure model, animal, Apoptosis, Nitric oxide, Caspase-3