Abstract

Obstructive sleep apnea syndrome (OSAS) is frequently associated with cardiovascular disease. We investigated endothelium-dependent and endothelium-independent nitric oxide-mediated vasodilatory function in normotensive patients with OSAS using the hand vein compliance technique.Dose-response curves to the endothelium-dependent vasodilator bradykinin were obtained in 23 male subjects with OSAS and 12 male control subjects of comparable age, height, and weight.Mean (+/- SD) maximum dilation (Emax) to bradykinin was significantly lower in OSAS patients than in controls (59.8 +/- 26.0 vs. 94.8 +/- 9.5%, p < 0.0001). Mean vasodilation with nitroglycerin was not diminished in the OSAS group (90.7 +/- 30.5 vs. 100.3 +/- 12.9% in controls; n.s.). In 11 OSAS patients, a follow-up investigation was performed after at least 2 months of treatment with nasal continuous positive airway pressure (CPAP): Emax to bradykinin rose from 54.5 +/- 19.2% to 111.5 +/- 25.1% after treatment (p < 0.001). Mean vasodilation to nitroglycerin was unchanged.These results suggest that endothelium-dependent nitric oxide-mediated vasodilation is impaired in patients with OSAS due to an impaired function in the endothelial cells. This impairment is reversible with CPAP treatment.

View details for PubMedID 11569627