[Obstructive sleep apnea syndrome: a cardiovascular risk factor?].
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Duchna
H W
HW
Poliklinik Abteilung für Pneumologie Allergologie und Schlafmedizin Bürkle-de-la-Camp-Platz 1 44789 Bochum, Germany. hans-werner-duchna@ruhr-uni-bochum.de
Guilleminault
C
C
Stoohs
R A
RA
Orth
M
M
de Zeeuw
J
J
Schultze-Werninghaus
G
G
Rasche
K
K
D001920:Bradykinin / Q000502:physiology; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000209:etiology*; D003627:Data Interpretation, Statistical; D004730:Endothelium, Vascular / Q000166:cytology / Q000503:physiopathology*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000502:physiology; D005996:Nitroglycerin; D017286:Polysomnography; D011175:Positive-Pressure Respiration; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy; D013997:Time Factors; D014664:Vasodilation
D009569:Nitric Oxide; D005996:Nitroglycerin; D001920:Bradykinin