Effects of acute through life-long hypoxic exposure on exercise pulmonary gas exchange

Improvement in lung diffusion by endothelin A receptor blockade at high altitude

“…Pharmacological pulmonary vasodilation improves the membrane component of lung diffusion in high-altitude newcomers, which may contribute to exercise capacity. altitude; hypoxia; lung diffusion; gas exchange; exercise capacity; pulmonary vascular resistance; pulmonary capillary pressure; pulmonary hypertension BOTH THE MEMBRANE AND THE capillary components of lung diffusing capacity have been shown to be increased in highaltitude residents (10,13,15,25). Increased lung diffusing capacity at high altitude allows for the preservation of gas exchange in the presence of a decreased ventilatory response at exercise (15).…”

“…Increased lung diffusing capacity at high altitude allows for the preservation of gas exchange in the presence of a decreased ventilatory response at exercise (15). High-altitude newcomers do not benefit from this adaptation (10,15,25) and, accordingly, depend on increased ventilation to maintain pulmonary gas exchange (15,45).Previous studies on lung diffusing capacity at high altitudes calculated the membrane and capillary components of alveolocapillary transfer of carbon monoxide (CO) using measurements at ambient air and increased inspired PO 2 (10,13,15,25). This approach rests on the PO 2 dependence of , the blood's specific transfer conductance of CO, in the Roughton and Forster equation, which states that 1/DL CO ϭ 1/Dm ϩ 1/ Vc where DL CO is the diffusing capacity of the lung for CO, Dm its membrane component, and Vc the capillary blood volume (37).…”

“…Increased lung diffusing capacity at high altitude allows for the preservation of gas exchange in the presence of a decreased ventilatory response at exercise (15). High-altitude newcomers do not benefit from this adaptation (10,15,25) and, accordingly, depend on increased ventilation to maintain pulmonary gas exchange (15,45).…”

“…Previous studies on lung diffusing capacity at high altitudes calculated the membrane and capillary components of alveolocapillary transfer of carbon monoxide (CO) using measurements at ambient air and increased inspired PO 2 (10,13,15,25). This approach rests on the PO 2 dependence of , the blood's specific transfer conductance of CO, in the Roughton and Forster equation, which states that 1/DL CO ϭ 1/Dm ϩ 1/ Vc where DL CO is the diffusing capacity of the lung for CO, Dm its membrane component, and Vc the capillary blood volume (37).…”

“…BOTH THE MEMBRANE AND THE capillary components of lung diffusing capacity have been shown to be increased in highaltitude residents (10,13,15,25). Increased lung diffusing capacity at high altitude allows for the preservation of gas exchange in the presence of a decreased ventilatory response at exercise (15).…”