Effects of sildenafil on exercise capacity in hypoxic normal subjects.
(2007) High Altitude Medicine and Biology (Print) — Vol. 8, n° 2, p. 155-163 (2007)
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- The phosphodiesterase-5 inhibitor sildenafil has been reported to improve hypoxic exercise capacity, but the mechanisms accounting for this observation remain incompletely understood. Sixteen healthy subjects were included in a randomized, double-blind, placebo-controlled, cross-over study on the effects of 50-mg sildenafil on echocardiographic indexes of the pulmonary circulation and on cardiopulmonary cycle exercise in normoxia, in acute normobaric hypoxia (fraction of inspired O2, 0.1), and then again after 2 weeks of acclimatization at 5000 m on Mount Chimborazo (Ecuador). In normoxia, sildenafil had no effect on maximum VO2 or O2 saturation. In acute hypoxia, sildenafil increased maximum VO2 from 27 +/- 5 to 32 +/- 6 mL/min/kg and O2 saturation from 62% +/- 6% to 68% +/- 9%. In chronic hypoxia, sildenafil did not affect maximum VO2 or O2 saturation. Resting mean pulmonary artery pressure increased from 16 +/- 3 mmHg in normoxia to 28 +/- 5 mmHg in normobaric hypoxia and 32 +/- 6 mmHg in hypobaric hypoxia. Sildenafil decreased pulmonary vascular resistance by 30% to 50% in these different conditions. We conclude that sildenafil increases exercise capacity in acute normobaric hypoxia and that this is explained by improved arterial oxygenation, rather than by a decrease in right ventricular afterload.
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Faoro, V., Lamotte, M., Deboeck, G., Pavelescu, A., Huez, S., Guenard, H., Martinot, J.-B., & Naeije, R. (2007). Effects of sildenafil on exercise capacity in hypoxic normal subjects. High Altitude Medicine and Biology (Print), 8(2), 155-163. https://doi.org/10.1089/ham.2007.1058 (Original work published 2007)