Objective: To investigate the mechanism of action in blood stasis syndrome of aged rats by Danshen injection. And the change of hemorheology and the components of erythrocyte membrane were studied. Method: Thirty Wistar rats which were 70-72 weeks were randomly assigned to Danshen injection high-dose group (drug 4.4 g·kg-1)

low-dose group (drug 1.1 g·kg-1) and model group with 10 rats in each group. Another ten younger Wistar rats were as young control group. The related indexes of hemorheology such as the whole blood viscosity

plasma viscosity

the red blood cell deformability and the components of erythrocyte membrane were determined after giving medicine 14 days by intraperitoneal injection. Result: Compared with the control group

the whole blood viscosity and plasma viscosity of the model group were increased (P<0.05

P<0.01). And the red blood cell deformability was decreased significantly under 200 s-1 and 500 s-1 (P<0.01) and 1 000 s-1 (P<0.01). Compared with the model group

the Danshen injection group was effective. The whole blood viscosity (P<0.01)

plasma viscosity (P<0.05)

the content of malondialdehyde (MDA) in erythrocyte membrane (P<0.01)were decreased. The red blood cell deformability (P<0.01) and the content of sialic acid

sulfhydryl

superoxide dismutase (SOD) and Na+-K+-ATPase activity (P<0.05) in erythrocyte membrane were increased. Conclusion: Danshen injection can improve the situation of blood stasis through increasing the content of sialic acid and SOD and reducing the content of MDA in erythrocyte membrane. It indicated that the metabolism of lipid was affected

ability of anti-oxidation was enhanced

the content of oxygen radical was decreased and the carrying capacity of negative charge in erythrocyte membrane was improved.