Bohr effect and slope of the oxygen dissociation curve after physical training

Abstract

Three O2 dissociation curves from venous blood [taken at rest (A), after in vitro acidification with lactic acid (B), and after exhaustive exercise (C)] were determined in eight athletes twice in a year in detrained and fully trained state. The steepness of the standard O2 dissociation curve becomes greater during the training period (increase in Hill's n from 2.68 +/- 0.10 to 2.96 +/- 0.15). There was a concomitant small rise in the intraerythrocytic organic phosphate concentrations. Bohr coefficients (BC) were calculated for blood O2 saturations ranging from 10 to 80% by comparing the dissociation curves A and B ("in vitro" BC) and curves A and C ("in vivo" BC). In detrained and trained state the in vivo BC show their maximal values at low saturation levels, in contrast the in vitro BC exhibit maximal values at middle saturations. During the training period there was an increase in the in vivo BC as well as in the in vitro BC at low saturations. These alterations may lead to augmented O2 extraction from a given volume of blood by up to 15% during heavy work in trained state. The reason for these observations could be an altered erythrocyte population.

Hemoglobin Oxygen Affinity in Patients with Cystic Fibrosis

“…Recently similar results were found at 3600 m of altitude [13], [14]. Interestingly at low saturations “standardized” in vivo PO 2 /SO 2 pairs tend to lie right of the in vitro curve, especially in venous blood returning from exercising muscles [36]–[38], [55], [60]. The result of this opposite changes is a markedly steepened complete in vivo oxygen dissociation curve probably in healthy subjects as well as in CF patients.…”

“…2 mmHg) but 17 differences amount to more than 4 mmHg. Differences in ODCs as well as BCs between fresh blood immediately after sampling and blood after equilibration in tonometers have occasionally been observed (e. g. [38], [60]). Concentration changes of BPG, ATP, Cl − , nitrocompounds or glutathione are possible causes.…”

Red Blood Cell Function in Hypoxia at Altitude and Exercise

“…The steep part of the ODC at low P02 is important for oxygen release from Hb to the tissues, since with an only small drop in the tissue or blood P02 a great amount of oxygen can be unloaded from Hb. Also, with a certain amount of 02 unloaded from Hb (arteriovenous 02-difference, AVDO2) the P02 in blood stays higher with a steep ODC than with a flat curve (16,106). This is of importance, since the P02 determines the diffusion of 02 from blood into the tissue.…”

Determinants of oxygen delivery and hemoglobin saturation during incremental exercise in horses

“…The P50 at maximal exercise (29.3 to 35.0 mm Hg) was increased 9 ± 4 mm Hg, a difference similar to that seen in humans at maximal exercise (approx 12 mm Hg). 7 This increase in P50 could be attributed entirely to the Bohr effect 13 mediated by the metabolic component of exercise-induced acidosis.…”

“…5 This rightward shifting of the ODC facilitates the release of hemoglobin-bound O 2 . 6 Affinity of hemoglobin for O 2 is in dynamic flux, depending on mediators in solution 7 and changes from arterial to venous blood. Mediators that change the affinity of hemoglobin for O 2 include CO 2 , 2,3-diphosphoglycerate (DPG), chloride, pH, and temperature, all of which change during exercise.…”