Effects of obstructive sleep apnea on endothelin-1 and blood pressure

Objective To evaluate blood pressure and humoral vasoconstrictor responses to recurrent episodes of obstructive sleep apnea and the effects of therapy by means of continuous positive airway pressure. Patients and methods We prospectively evaluated overnight changes in hemody namics, oxygen saturation, the apnea-hypopnea index, circulating endothelin -1, norepinephrine and plasma renin activity in 22 patients with severe obs tructive sleep apnea before and after successful therapy using continuous p ositive airway pressure therapy (three measurements). Measurements of endot helin-1 and blood pressure were also obtained on three occasions, at simila r times, in 12 healthy control subjects without sleep disturbances. Results Mean arterial pressure and endothelin-1 concentrations increased si gnificantly after 4 h of untreated obstructive sleep apnea, and decreased a fter 5 h of continuous positive airway pressure. Changes in endothelin-1 le vels were correlated with changes in mean arterial pressure (r = 0.44, P < 0.02) and with changes in oxygen saturation (r = 0.37, P < 0.05). Norepinep hrine levels and plasma renin activity did not change significantly in pati ents with obstructive sleep apnea, and were not correlated with changes in blood pressure or oxygen saturation. In controls, blood pressure measuremen ts at similar times during the night showed changes directionally opposite to that seen in obstructive sleep apnea, while endothelin-1 levels remained unchanged. Conclusions Sleep apnea elicits increases in blood pressure and endothelin- 1, with reductions in both after treatment. Vasoconstrictor and mitogenic e ffects of endothelin-1 may be implicated in increased cardiovascular risk i n patients with obstructive sleep apnea, J Hypertens 1999, 17:61-66 (C) Lip pincott Williams & Wilkins.