Aim To observe the levels of nitric oxide,endothelin-1 and soluble P-selectin in patients with obstructive sleep apnea/hyponea syndrome and determine whether continuous positive airway pressure treatment has effect on them.Methods Blood concentration of nitric oxide,endothelin-1 and soluble P-selectin,the markers of vascular endothelial cell function,were determined by nitrate reductase,radioimmunoassay,and enzyme-linked immunoassay,respectively.Results Compared with healthy controls(83.26±47.74 μmol/L,58.49±15.02 ng/L and 32.90±55.73 mg/L;respectively),the levels of nitric oxide,endothelin-1 and soluble P-selectin both in patients without cardiovascular disease(63.41±27.68 μmol/L,71.56±23.33 ng/L and 131.13±77.93 mg/L;p<0.05)and in those with cardiovascular disease(59.59±34.19 μmol/L,89.01±44.87 ng/L and 160.83±125.45 mg/L;p<0.05)were significantly changed.However,after continuous positive airway pressure treatment,the blood concentration of nitric oxide(60.46±23.53 μmol/L vs 75.11±23.91 μmol/L;P=0.025),endothelin-1(73.60±20.78 ng/L vs 61.84±18.79 ng/L;P=0.031)and soluble P-selectin(137.34±90.35 mg/L vs 89.56±34.60 mg/L;P=0.013)were significantly improved.Conclusions Obstructive sleep apnea/hyponea syndrome patients,no matter whether complicated by cardiovascular diseases or not,have significant vascular endothelial cell dysfunction,which can be improved through the continuous positive airway pressure treatment.