Objective:The present study was designed to investigate the protective effect of astragaloside IV on mitochondrial injury of aortic endothelial cells from renovascular hypertensive rats. Methods:Two kidney one clip (2K1C) technique was performed to prepare renovascular hypertensive rats. Two weeks after operation,the rats were divided into two groups,the operation group and the astragaloside Ⅳ treatment group[5.0 mg/(kg-d)]. The sham operated rats were used as normal control. After treatment for two weeks,the mitochondrial ultrastructure of thoracic aortic endothelial cells from the rats was observed. The expression of Mn-superoxide dismutase (SOD2) in thoracic aortic endothelium was observed by immunohistochemical staining. Results:Two weeks after operation,the rats showed significant increase of systolic blood pressure compared to that of control rats. The thoracic aortic endothelial cell mitochondria of hypertensive rats showed fracture and disappearance of cristae,swelling and vacuolation as well as decreased mitochondrial matrix electron density. These changes of mitochondrial were ameliorated significantly by astragaloside Ⅳ. In addition,astragaloside Ⅳ augmented the lower expression level of SOD2 in the aortic endothelium from the hypertensive rats compared with that from the normal controls. Conclusion:Astragaloside Ⅳ reverses mitochondrial injury of aortic endothelial cells from renovascular hypertensive rats,which may be linked to its ability to increase SOD2 expression in the aortic endothelium of the rats.