Objective To explore the possible mechanism of sleep apnea causing atherosclerosis by observe the oxidative stress reaction in the animal models with experimental obstructive sleep apnea syndrome.Methods Sixteen Chinese miniature pigs were equally divided into obstructive sleep apnea(OSA) group and control group.Animal models were made by gel injection method in OSA group.Before surgery and 12 weeks after surgery,venous blood was obtained from experimental animals to measure xanthine oxidase(XOD),superoxide dismutase(SOD) and malondialdehyde(MDA).Results(1) After surgery,the level of XOD was obviously elevated in OSA group,increasing from(3.71±0.07) to(4.82±0.08) U/L.Significant difference existed in the XOD level between before and after surgery.No significant change in the level of XOD was found in control group after surgery.There was significant difference in the XOD level between OSA and control groups after surgery.(2) After surgery,the level of SOD depressed from(142.33±6.82) to(121.21±1.93) NU/ml in OSA group.Significant difference existed in the SOD level between before and after surgery.The level of MDA was obviously elevated in OSA group after surgery,increasing from(3.66±0.47) to(5.59±0.75) μmol/L.Significant difference existed in the MDA level between before and after surgery.In control group,there were no significant changes in the levels of SOD and MDA after surgery.Significant differences existed in SOD and MDA between OSA and control groups after surgery(P<0.05).Conclusion Experimental obstructive sleep apnea can put the animals into oxidative stress state and produce a large amount of oxygen free radicals.Increased oxygen free radicals induce a series of pathophysiological reactions and promote the initiation and development of atherosclerosis.