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Role of endothelin-1 in exposure to high altitude: Acute Mountain Sickness and Endothelin-1 (ACME-1) study.

Author(s): Modesti PA, Vanni S, Morabito M, Modesti A, Marchetta M, Gamberi T, Sofi F, Savia G, Mancia G, Gensini GF, Parati G

Affiliation(s): Clinica Medica Generale e Cardiologia, University of Florence, Viale Morgagni 85, 50134 Florence, Italy. pamodesti@unifi.it

Publication date & source: 2006-09-26, Circulation., 114(13):1410-6. Epub 2006 Sep 18.

Publication type: Randomized Controlled Trial

BACKGROUND: The degree of pulmonary hypertension in healthy subjects exposed to acute hypobaric hypoxia at high altitude was found to be related to increased plasma endothelin (ET)-1. The aim of the present study was to investigate the effects of ET-1 antagonism on pulmonary hypertension, renal water, and sodium balance under acute and prolonged exposure to high-altitude-associated hypoxia. METHODS AND RESULTS: In a double-blind fashion, healthy volunteers were randomly assigned to receive bosentan (62.5 mg for 1 day and 125 mg for the following 2 days; n=10) or placebo (n=10) at sea level and after rapid ascent to high altitude (4559 m). At sea level, bosentan did not induce any significant changes in hemodynamic or renal parameters. At altitude, bosentan induced a significant reduction of systolic pulmonary artery pressure (21+/-7 versus 31+/-7 mm Hg, P<0.03) and a mild increase in arterial oxygen saturation versus placebo after just 1 day of treatment. However, both urinary volume and free water clearance (H2OCl/glomerular filtration rate) were significantly reduced versus placebo after 2 days of ET-1 antagonism (1100+/-200 versus 1610+/-590 mL; -6.7+/-3.5 versus -1.8+/-4.8 mL/min, P<0.05 versus placebo for both). Sodium clearance and segmental tubular function were not significantly affected by bosentan administration. CONCLUSIONS: The present results indicate that the early beneficial effect of ET-1 antagonism on pulmonary blood pressure is followed by an impairment in volume adaptation. These findings must be considered for the prevention and treatment of acute mountain sickness.

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