Abstract: To investigate changes and intercorrelation of heme oxygenase-1(HO-1)/carbon monoxide(CO) and nitric oxide synthase (NOS)/nitric oxide(NO) and the effect of simvastatin on them in atherosclerotic progress. Methods16 rabbits had a 1% cholesterol diet for eight weeks and after eight weeks were fed with normal diets for eight weeks and then were divided into two groups: the simvastatin group and the model group, 8 rats fed with normal diets served as the control group. Levels of serum lipids, serum NO and plasma CO were determined at the beginning, the 8th week and the 16th week, and also the expressions of HO-1 and NOS in the thoracia aortic tissues were determined by the immunohistochemistry technique. ResultsAt the end of the 8th week, levels of serum lipids and plasma CO were increased in the simvastatin group (P＜0.01) and the level of serum NO and expressions of HO-1 and inducible nitric oxide synthase (iNOS) were decreased compared with the control group (P＜0.01). At the end of the 16th week, levels of serum lipids and plasma CO and expressions of HO-1 and iNOS were significantly decreased (P＜0.01), with the model group. Conclusions In atherosclerotic progress, HO1/CO and NOS/NO systems have a reciprocal relationship, and simvastatin may delay the atherosclerotic progress by decreasing the two systems.

Key words: Atherosclerosis, Heme oxygenase, Carbon monoxide, Nitric oxide synthase, Nitric oxide, Simvastatin, Immunohistochemistry