Effects of high-altitude chronic hypoxia on platelet α2-receptors in man

M. Zaccaria, P. A. Borea, G. Opocher, A. Ponchia, K. Varani, D. Fraccarollo, C. Scandellari

Research output: Contribution to journalArticle

Abstract

During chronic high-altitude (HA) exposure, basal and exercise-induced noradrenaline (NA) increases do not parallel blood pressure (BP) changes observed; unlike β-adrenergic receptors, to our knowledge no data are available on α-receptors. We studied platelet α2- and leucocyte β-receptors and basal catecholamine levels in 11 trained climbers before and after they had spent a 15-day period at a height of over 4400 m. In six of the climbers we also evaluated catecholamines after maximal bicycle ergometer exercise. After chronic high-altitude exposure, a significant decrease was found in platelet α2-receptor density and affinity [B(max) from 92.6 ± 6.7 to 54.6 ± 4.2 fmol mg-1 protein (P <0.001) and K(D) from 1.271 ± 0.034 to 1.724 ± 0.077 nmol L-1 (P <0.05)], although no changes to β-receptors were observed. No changes were found in basal pre- and post-expedition NA and adrenaline (A), and there was only a slight decrease in post-expedition NA after maximal exercise. Our results suggest that prolonged exposure to hypoxia induces a down-regulation of α2-receptors, which may be a contributory factor in the regulation of the physiological vascular response to acclimatization.

Original languageEnglish
Pages (from-to)316-321
Number of pages6
JournalEuropean Journal of Clinical Investigation
Volume27
Issue number4
Publication statusPublished - 1997

Keywords

  • α-receptor
  • β-receptor
  • Adrenaline
  • High altitude
  • Hypoxia
  • Noradrenaline

ASJC Scopus subject areas

  • Medicine(all)

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