Journal of Applied Physiology, Vol 67, Issue 6 2286-2295, Copyright © 1989 by American Physiological Society

ARTICLES

Effects of altitude acclimatization on pulmonary gas exchange during exercise

D. E. Bebout, D. Story, J. Roca, M. C. Hogan, D. C. Poole, R. Gonzalez-Camarena, O. Ueno, P. Haab and P. D. Wagner
Department and School of Medicine, University of California, San Diego, La Jolla 92093.

Pulmonary gas exchange was studied in eight normal subjects both before and after 2 wk of altitude acclimatization at 3,800 m (12,470 ft, barometric pressure = 484 Torr). Respiratory and multiple inert gas tensions, ventilation, cardiac output (Q), and hemoglobin concentration were measured at rest and during three levels of constant-load cycle exercise during both normoxia [inspired PO2 (PIO2) = 148 Torr] and normobaric hypoxia (PIO2 = 91 Torr). After acclimatization, the measured alveolar-arterial PO2 difference (A-aPO2) for any given work rate decreased (P less than 0.02). The largest reductions were observed during the highest work rates and were 24.8 +/- 1.4 to 19.7 +/- 0.8 Torr (normoxia) and 22.0 +/- 1.1 to 19.4 +/- 0.7 Torr (hypoxia). This could not be explained by changes in ventilation-perfusion inequality or estimated O2 diffusing capacity, which were unaffected by acclimatization. However, Q for any given work rate was significantly decreased (P less than 0.001) after acclimatization. We suggest that the reduction in A-aPO2 after acclimatization is a result of more nearly complete alveolar/end-capillary diffusion equilibration on the basis of a longer pulmonary capillary transit time.

This article has been cited by other articles:

				I. Vogiatzis, S. Zakynthinos, R. Boushel, D. Athanasopoulos, J. A. Guenette, H. Wagner, C. Roussos, and P. D. Wagner The contribution of intrapulmonary shunts to the alveolar-to-arterial oxygen difference during exercise is very small J. Physiol., May 1, 2008; 586(9): 2381 - 2391. [Abstract] [Full Text] [PDF]

				A. C. Henderson, D. L. Levin, S. R. Hopkins, I. M. Olfert, R. B. Buxton, and G. K. Prisk Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow J Appl Physiol, August 1, 2006; 101(2): 583 - 589. [Abstract] [Full Text] [PDF]

				I. M. Olfert, J. Balouch, A. Kleinsasser, A. Knapp, H. Wagner, P. D. Wagner, and S. R. Hopkins Does gender affect human pulmonary gas exchange during exercise? J. Physiol., June 1, 2004; 557(2): 529 - 541. [Abstract] [Full Text] [PDF]

				J. A. L. Calbet, R. Boushel, G. Radegran, H. Sondergaard, P. D. Wagner, and B. Saltin Why is VO2 max after altitude acclimatization still reduced despite normalization of arterial O2 content? Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2003; 284(2): R304 - R316. [Abstract] [Full Text] [PDF]

				H. J. Bogaard, S. R. Hopkins, Y. Yamaya, K. Niizeki, M. G. Ziegler, and P. D. Wagner Role of the autonomic nervous system in the reduced maximal cardiac output at altitude J Appl Physiol, July 1, 2002; 93(1): 271 - 279. [Abstract] [Full Text] [PDF]

				K. Katayama, Y. Sato, Y. Morotome, N. Shima, K. Ishida, S. Mori, and M. Miyamura Intermittent hypoxia increases ventilation and SaO2 during hypoxic exercise and hypoxic chemosensitivity J Appl Physiol, April 1, 2001; 90(4): 1431 - 1440. [Abstract] [Full Text] [PDF]

				S. R. Hopkins, R. C. Barker, T. D. Brutsaert, T. P. Gavin, P. Entin, I. M. Olfert, S. Veisel, and P. D. Wagner Pulmonary gas exchange during exercise in women: effects of exercise type and work increment J Appl Physiol, August 1, 2000; 89(2): 721 - 730. [Abstract] [Full Text] [PDF]