Objective:To investigate the changes of reactive oxygen species(ROS)and Glutathione(GSH) and their chronological order in the apoptosis of K562 cells induced by simvastatin to explore the apoptosis mechanism.Methods:K562 cells cultivated in routine method for 24h were exposed in the simvastatin 20μmol/L.Cell morphological analysis were conducted at 48h and the vitalities of K562 cells were cultivated detected with MTT at different times(12

24

48

72 h) respectively.Fluorochrome flow cytometry was performed to detect cell apoptotic ratio and changes of intracellular ROS.The content of intracellular GSH in K562 cells was measured by colorimetric method.Results:K562 cells presented typical apoptosis morphological changes the treatment of simvastatin for 48h.cell inhibition ratio at different times(12

24

48

and 72 h) were 0

(19.02±0.92)%

(56.4±3.20)%

(74.4±5.54)% respectively and cell growth of K562 was inhibited.The apoptotic ratio were(2.55±0.25)%

(6.1±0.35)%

(14.15±0.42)%

and(30.70±0.65)% respectively.Furthermore

the changes of fluorescence intensity of ROS were also significantly increased(P<0.05) in K562 cells compared with the control groups

the changes of fluorescence intensity were 1.61±0.15

13.1±1.59

10.0±1.05

and 8.10±0.87mg/gprot respectively groups at different times(12

24

48 and 72h).The content of intracellular GSH in K562 cells GSH were 274.7±11.5

262.5±9.8

272.4±10.5

and 357.2±16.8 mg/gprot at different times(12

24

48 and 72 h) respectively.And there was a markedly decrease of the intracellular GSH in K562 cells compared with the control groups(P<0.05).Conclusion:K562 cells could be induced apoptosis by simvastatin.The increase of the GSH and decrease of the ROS are the early events of the K562 cells apoptosis induced by simvastatin.The potential mechanism of the K562 cells apoptosis may be related to the disequilibrium of oxidation-reduction system.