title: Effects of five nights of normobaric hypoxia on the ventilatory responses to acute hypoxia and hypercapnia.
abstract: This study examined the effects of five nights of normobaric hypoxia on ventilatory responses to acute isocapnic hypoxia (AHVR) and hyperoxic hypercapnia (AHCVR). Twelve male subjects (26.6 +/- 4.1 years, standard deviation (S.D.)) slept 8-9 h per day overnight for 5 consecutive days at a simulated altitude of 4,300 m (FiO2= approximately 13.8%). Using the technique of dynamic end-tidal forcing, the AHVR and AHCVR were assessed twice prior to, immediately after, and 5 days following the hypoxic exposure. Immediately following the exposure, AHVR was increased by 1.6 +/- 1.3 L min(-1) %(-1) (P<0.01) when compared with control values. Likewise, after the exposure, ventilation in hyperoxia was increased (P<0.001) and was associated with both an increase in the slope (1.5 +/- 1.4 L min(-1) Torr(-1); P<0.05) and decrease in the intercept (-2.7 +/- 4.3 Torr; P<0.05) of the AHCVR. These results show that five nights of hypoxia can elicit similar perturbations, in both AHVR and AHCVR, as have been reported during more chronic altitude exposures.
authors: Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Heritage Medical Research Building Room 209, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
authors: Philip N
authors: PN
authors: Ainslie
authors: Jon C
authors: JC
authors: Kolb
authors: Kojiro
authors: K
authors: Ide
authors: Marc J
authors: MJ
authors: Poulin
mesh_terms: D000328:Adult; D000531:Altitude; D000704:Analysis of Variance; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000378:metabolism; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D013997:Time Factors; D014691:Ventilation / Q000379:methods
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen