Aim To investigate whether atorvastatin dose-dependently affects endothelial progenitor cells(EPC) mobilization from peripheral blood,EPC numbers in bone marrow culture in vitro and endothelial function after myocardial injury rats.Methods Rats with myocardial injury,induced by isoprenaline,were randomized to treatment groups with vehicle or atorvastatin [5,10,20,40 and 80 mg/(kg·d)] for 4 weeks starting on one day after Myocardial injury.Putative precursor populations [CD34+/vascular endothelial growth factor receptor 2(VEGFR-2)+ haematopoietic stem cells] were measured by flow cytometric analysis.Total mononuclear cells(MNC) were isolated from peripheral blood by Ficoll density gradient centrifugation,and the cells were plated on gelatin coated culture dishes.Double-stained cells for both FITC BS-1 lectin and acLDL-DiI were counted as EPC in at least 3 randomly selected HPF.Serum concentration of nitric oxide(NO) was measured after atorvastatin use.Results Atorvastatin increased EPC numbers both in bone marrow and peripheral blood culture in vitro,maximum at 40 mg/(kg·d)(p<0.05).EPC numbers at the dose of 80 mg/(kg·d) were slightly reduced comparing with 40 mg/(kg·d),but there was no statistical difference;circulating EPC(double positive CD34+/VEGFR-2+) were significantly elevated after myocardial injury(p<0.05);EPC mobilization was markedly further augmented by atorvastatin treatment,maximum at 80 mg/(kg·d)(4.18-fold increase,p<0.05).There was no statistical difference between 40 mg/(kg·d) and 80 mg/(kg·d);Atorvastatin induced a dose-dependent increase in serum concentration of NO generation,with maximal effect at 80 mg/(kg·d).Conclusions Atorvastatin dose-dependently improve EPC mobilization,EPC numbers in vitro culture and endothelial function.