Totally 60 SD rats were randomly divided into control group， model group， low dose of NAC group and high dose of NAC group，with 15 rats in each group. Except for control group， the rats in all other groups were administered with potassium oxonate to induce the HUA models. The rats in low and high doses of NAC groups were given 75 and 300 mg·kg^－1 NAC respectively by gavage， while the rats in control group and model group were given the same amount of normal saline， once a day for 4 weeks. The blood samples of rats were collected from abdominal aorta and the serum was separated. The levels of serum uric acid （UA）， blood urea nitrogen （BUN）， serum creatinine （Scr）， endoderin-1 （ET-1）， nitric oxide （NO） and malondialdehyde （MDA）， and the activities of total superoxide dismutase （T-SOD）， catalase （CAT）， and glutathione peroxidase （GSH-Px） were measured. The expression levels of endothelial nitric oxide synthase （eNOS） in thoracic aorta tissue of the rats in various groups were detected by immunohistochemistry method.

Compared with control group， the levels of UA， MDA and ET-1 of the rats in model group were obviously increased （P<0.05）， the activities of serum T-SOD， CAT and GSH-Px， the level of NO and the expression level of eNOS in thoracic aorta tissue were significantly decreased （P<0.05）， while there were no statistical differences in the levels of serum BUN and Scr （P>0.05）. Compared with model group， the levels of serum UA， MDA and ET-1 in high dose of NAC group were significantly decreased （P<0.05）， the activities of serum T-SOD， CAT， and GSH-Px， the level of NO and the expression level of eNOS in thoracic aorta tissue were markedly increased （P<0.05）， while there were no statistical differences in the levels of serum BUN and Scr （P>0.05）； there were no statistical differences in the changes of the above indexes in low dose of NAC group （P>0.05）. Compared with low dose of NAC group， the levels of serum UA， MDA and ET-1 of the rats in high dose of NAC group were significantly decreased （P<0.05）， the activities of serum T-SOD， CAT， and GSH-Px， the level of NO and the expression level of eNOS in thoracic aorta tissue were markedly increased （P<0.05），while there were no statistical differences in the levels of serum BUN and Scr （P>0.05）.

NAC can decrease the level of serum UA in the HUA rats， reduce the level of oxidative stress in the body， and improve the vascular endothelial function.