title: Ventilatory and cardiovascular responses to hypoxia and exercise in Andean natives living at sea level.
abstract: This study was designed to determine in subjects born at high altitude who move to sea level (HA-SL: born at 3500 m or above; n = 25) whether their cardiorespiratory responses to hypoxia and exercise are similar to those of sea level natives (SL,n = 25). The average age (39 +/- 7.3 yr), weight (72 +/- 7.3 kg), and height (1.71 +/- 0.01 m) did not differ between the SL and HA-SL subjects. All subjects were studied at rest or during exercise (60 W on cycle ergometer) while breathing room air (F(IO2) = 0.21 and P(B) = 760) or hypoxia (F(IO2) = 0.115 and PB = 760) in the following order: (1) normoxia at rest (NX-Rs), (2) hypoxia at rest (HX-Rs, 11.5% O(2)), hypoxia at exercise (HX-Ex), and normoxia at exercise (NX-Ex). Each period lasted 5 min. In absolute values, HA-SL showed significantly higher ventilation (V(E), L/min) during exercise in both normoxia and hypoxia and higher oxygen saturation (Sa(O2), %) during hypoxia both at rest and in exercise. They also had lower end-tidal CO(2) values (P(ETCO2), torr) at rest in both normoxia and hypoxia, but a higher P(ETCO2) in hypoxic exercise. Heart rate (HR, beats/min) was lower at rest in both normoxia and hypoxia, but higher in exercise. With acute hypoxia, Sa(O2) decreased less in the HA-SL than in the SL at rest (HA-SL, 9.2 +/- 0.8; SL, 12.0 +/- 0.82) and during exercise (HA-SL, 18.3 +/- 1.1; SL, 21.2 +/- 1.2). In conclusion, this study shows that HA-SL natives have increased ventilation and heart rate during exercise once their lifelong hypoxia is relieved.
authors.affiliation: Cayetano Heredia University/IIA, Department of Physiological Sciences, Oxygen Transport Laboratory, Apartado 4314, Lima 100, Perú. agamboa@amauta.rcp.net.pe
authors.forename: A
authors.initials: A
authors.lastname: Gamboa
authors.forename: F
authors.initials: F
authors.lastname: León-Velarde
authors.forename: M
authors.initials: M
authors.lastname: Rivera-Ch
authors.forename: M
authors.initials: M
authors.lastname: Vargas
authors.forename: J A
authors.initials: JA
authors.lastname: Palacios
authors.forename: C
authors.initials: C
authors.lastname: Monge-C
mesh_terms: D000064:Acclimatization; D000328:Adult; D000531:Altitude; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007198:Indians, North American; D008297:Male; D008875:Middle Aged; D012119:Respiration; D012129:Respiratory Function Tests