Effects of High Altitude (Low Arterial $${{\text{P}}_{{O_2}}}$$ ) and of Displacements of the Oxygen Dissociation Curve of Blood on Peripheral O2 Extraction and $${{\text{P}}_{{O_2}}}$$

Abstract

The rise in 2,3-diphosphoglycerate (2,3-DPG) content of human erythrocytes occurring at high altitude (caused by the rise in blood and red cell pH, respectively, and by the increased mean desaturation of hemoglobin) and the resulting right-hand shift of the oxyhemoglobin dissociation curve of blood serve to counterbalance the left-hand shift resulting from the hypoxiainduced respiratory alkalosis (mediated by the Bohr eifect(s) of hemoglobin). Accordingly, the main role of the 2,3-DPG change at high altitude (and also in acid-base disorders) is to maintain the oxygen dissociation curve of human blood at (or near) its original position. This conclusion seems to be valid for man resting at altitudes up to 7000 m. The changes occurring at higher altitudes and during a rapid climb to a summit above 8000 m remain to be investigated.