Objective To investigate the mechanism of Tongxinluo Superfine Powder（Powder for removing obstruction of collaterals） in protecting the endothelium by observing the endothelium oxidative injury caused by nicotinamide adenine dinucleotide phosphate（NADPH） in rats with qi deficiency and blood-stasis blocking collaterals.Methods The animal model of "qi deficiency and blood-stasis blocking collaterals" was induced by starvation and exhaustion exercise in 8-week-old SD rats and endothelium injury was established by angiotensinⅡ infusion at a rate of 200ng/kg per min.The SD rats were randomly divided into 3 groups:control group

model group and Tongxinluo group with 10 in each.After treatment of 14 days

the content of endothelin（ET）

nitric oxide（NO）

angiotensin Ⅱ（AngⅡ）

interleukin-6（IL-6） and tumor necrosis factor-α（TNF-α）

morphology of endothelial cells in the thoracic aorta

and the nuclear kappa B（NF-κB）

vascular cell adhesion molecule-l（VCAM-1） and endothelial nitric oxide synthase（eNOS） expression in aorta were observed.Results In the model group

there existed the massive cell detachments in vascular endothlium

while in Tongxinluo group

only a mild injury was observed.The blood ET

IL-6 and TNF-α increased（P<0.05 or P<0.01）

NO decreased（P<0.05） in the model group

while in Tongxinluo group

the result was opposite.The p22phox mRNA（P<0.01）

NF-κB

and VCAM-1 expression increased significantly in the model group

moreover

eNOS expression decreased.These changes in Tongxinluo group were reversed to different degrees.Conclusion Tongxinluo protects endothelium by inhibiting NADPH-oxidation-inflammatory injury of vessels in rats with qi deficiency and blood-stasis blocking collaterals.