AimTo clarify the effects of the cardiac mast cells on cardiac function after myocardial infarction(MI),and to study the relationship between mast cells and ventricular remodeling after MI in SD rats.MethodsMI model was established in male Sprague-Dawley（SD） rats by ligation of left anterior descending coronary artery.The rats were randomly divided into three groups before 5 days of ligation：sham-operated group(n=6)，MI model group(n=8) and mast cell stabilizer cromolyn sodium treatment group(n=7).Before 3 days, after 2 and 4 weeks of ligation, the cardiac function was assessed by Echocardiography.After 4 weeks of treatment, the ratio of left or right ventricular weight and body weight were measured，the change of histopathological were observed, and the density of mast cells were measured.ResultsAs compared with sham-operated group, left ventricular ejection fraction(EF) in MI model group and treatment group was markedly decreased(p<0.01)after 2 weeks of treatment.Although the enlargement of the heart has been going in model group and treatment group, there is no significant difference among these three groups.After 4 weeks of the treatment, the Left ventricular end-diastolic volume(EDV) was significantly increased in model group and treatment group more than in sham-operated group（p<0.05）.Compared with MI model group，cromolyn sodium increased EF but not EDV, and decreased left ventricular index(p<0.05) and mast cells density(p<0.01) in left ventricular subepicardial layers of infarted region.The number of mast cells in subepicardial layers had negative correlation with EF, but was