Oxygen transport in blood at high altitude: role of the hemoglobin-oxygen affinity and impact of the phenomena related to hemoglobin allosterism and red cell function

Eur J Appl Physiol. 2003 Oct;90(3-4):351-9. doi: 10.1007/s00421-003-0954-8. Epub 2003 Sep 18.


Altitude hypoxia is a major challenge to the blood O2 transport system, and adjustments of the blood-O2 affinity might contribute significantly to hypoxia adaptation. In principle, lowering the blood-O2 affinity is advantageous because it lowers the circulatory load required to assure adequate tissue oxygenation up to a threshold corresponding to about 5,000 m altitude, whereas at higher altitudes an increased blood-O2 affinity appears more advantageous. However, the rather contradictory experimental evidence raises the question whether other factors superimpose on the apparent changes of the blood-O2 affinity. The most important of these are as follows: (1) absolute temperature and temperature gradients within the body; (2) the intracapillary Bohr effect; (3) the red cell population heterogeneity in terms of O2 affinity; (4) control of altitude alkalosis; (5) the possible role of hemoglobin as a carrier of the vasodilator nitric oxide; (6) the effect of varied red cell transit times through the capillaries.

Publication types

  • Review

MeSH terms

  • Allosteric Regulation
  • Altitude*
  • Animals
  • Carbon Dioxide / blood
  • Cardiac Output / physiology
  • Diffusion
  • Erythrocyte Aging / physiology
  • Erythrocytes / metabolism
  • Erythrocytes / physiology*
  • Hemoglobins / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Hypoxia / physiopathology
  • Models, Molecular
  • Nitric Oxide / metabolism
  • Nitric Oxide / physiology
  • Oxygen / blood*
  • Oxygen / metabolism
  • Partial Pressure
  • Protein Binding / physiology
  • Temperature


  • Hemoglobins
  • Carbon Dioxide
  • Nitric Oxide
  • Oxygen