Journal of Applied Physiology, Vol 76, Issue 3 1055-1059, Copyright © 1994 by American Physiological Society

ARTICLES

Adrenergic status of humans during prolonged exposure to the altitude of 6,542 m

A. M. Antezana, R. Kacimi, J. L. Le Trong, M. Marchal, I. Abousahl, C. Dubray and J. P. Richalet
Association pour la Recherche en Physiologie de l'Environnement, Bobigny, France.

Plasma norepinephrine (NE) concentration increases with altitude exposure while maximal heart rate (HR) and chronotropic response to isoproterenol (IP) are blunted. Downregulation of cardiac beta-adrenergic receptors (beta-AR) has been evoked to explain this phenomenon. Chronotropic response was studied at extreme altitude in 10 subjects (4 women, 6 men; aged 35 +/- 6 yr). Observations were made in normoxia (N) and after 1 (H1) and 3 (H3) wk at 6,542 m. Acclimatization was accomplished by gradual climbing from 4,000 to 6,542 m over 10 days. Plasma NE was obtained at rest and during submaximal exercise. Successive doses of IP (0.02, 0.04, and 0.06 microgram/kg-1.min-1) were infused for 5 min each. Density and affinity of lymphocyte beta 2-AR were also measured. Increase in HR for maximal dose of IP decreased from 57 +/- 12 to 34 +/- 7 and 37 +/- 10 min-1 in H1 and H3, respectively (P < 0.001 for both). IP dose for which HR rises by 25 min-1 (I25) increased from 27 +/- 5 in N to 42 +/- 10 and 43 +/- 17 ng.kg-1.min-1 in H1 and H3, respectively (P < 0.001 for both). Arterial O2 saturation at rest was 98 +/- 2% in N, 72 +/- 6% in H1 (P < 0.001), and 79 +/- 5% in H3 (P < 0.001). The chronotropic response was neither restored nor further attenuated after 3 wk at 6,542 m. Plasma NE levels at rest and during exercise were higher at 6,542 m than values obtained in previous studies at 4,350 and 4,800 m.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				P. L. Brubaker Adventure Travel and Type 1 Diabetes: The complicating effects of high altitude Diabetes Care, October 1, 2005; 28(10): 2563 - 2572. [Full Text] [PDF]

				M. B. Schindler, A. A. Hislop, and S. G. Haworth Postnatal Changes in Response to Norepinephrine in the Normal and Pulmonary Hypertensive Lung Am. J. Respir. Crit. Care Med., September 15, 2004; 170(6): 641 - 646. [Abstract] [Full Text] [PDF]

				J. Cornolo, P. Mollard, J. V. Brugniaux, P. Robach, and J.-P. Richalet Autonomic control of the cardiovascular system during acclimatization to high altitude: effects of sildenafil J Appl Physiol, September 1, 2004; 97(3): 935 - 940. [Abstract] [Full Text] [PDF]

				F. Favret, K. K. Henderson, J.-P. Richalet, and N. C. Gonzalez Effects of exercise training on acclimatization to hypoxia: systemic O2 transport during maximal exercise J Appl Physiol, October 1, 2003; 95(4): 1531 - 1541. [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]

				R. Boushel, J.-A. L. Calbet, G. Radegran, H. Sondergaard, P. D. Wagner, and B. Saltin Parasympathetic Neural Activity Accounts for the Lowering of Exercise Heart Rate at High Altitude Circulation, October 9, 2001; 104(15): 1785 - 1791. [Abstract] [Full Text] [PDF]

				F. Favret, K. K. Henderson, R. L. Clancy, J.-P. Richalet, and N. C. Gonzalez Exercise training alters the effect of chronic hypoxia on myocardial adrenergic and muscarinic receptor number J Appl Physiol, September 1, 2001; 91(3): 1283 - 1288. [Abstract] [Full Text] [PDF]

				F. Favret, J.-P. Richalet, K. K. Henderson, R. Germack, and N. C. Gonzalez Myocardial adrenergic and cholinergic receptor function in hypoxia: correlation with O2 transport in exercise Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2001; 280(3): R730 - R738. [Abstract] [Full Text] [PDF]

				H. J. Green, B. Roy, S. Grant, R. Hughson, M. Burnett, C. Otto, A. Pipe, D. McKenzie, and M. Johnson Increases in submaximal cycling efficiency mediated by altitude acclimatization J Appl Physiol, September 1, 2000; 89(3): 1189 - 1197. [Abstract] [Full Text] [PDF]

				S. S. Salvi {alpha}1-Adrenergic Hypothesis for Pulmonary Hypertension Chest, June 1, 1999; 115(6): 1708 - 1719. [Abstract] [Full Text] [PDF]

				X.-Q. Hu, S. Yang, W. J. Pearce, L. D. Longo, and L. Zhang Effect of Chronic Hypoxia on Alpha-1 Adrenoceptor-Mediated Inositol 1,4,5-Trisphosphate Signaling in Ovine Uterine Artery J. Pharmacol. Exp. Ther., March 1, 1999; 288(3): 977 - 983. [Abstract] [Full Text]