Influence of carbon monoxide on hemoglobin-oxygen binding

J Appl Physiol. 1976 Dec;41(6):893-9. doi: 10.1152/jappl.1976.41.6.893.


The oxygen dissociation curve and Bohr effect were measured in normal whole blood as a function of carboxyhemoglobin concentration [HbCO]. pH was changed by varying CO2 concentration (CO2 Bohr effect) or by addition of isotonic NaOH or HCl at constant PCO2 (fixed acid Bohr effect). As [HbCO] varied through the range of 2, 25, 50, and 75%, P50 was 26.3, 18.0, 11.6, and 6.5 mmHg, respectively. CO2 Bohr effect was highest at low oxygen saturations. This effect did not change as [HbCO] was increased. However, as [HbCO] was increased from 2 to 75%, the fixed acid Bohr factor increased in magnitude from -0.20 to -0.80 at very low oxygen saturations. The effect of molecular CO2 binding (carbamino) on oxygen affinity was eliminated at high [HbCO]. These results are consistent with the initial binding of O2 or CO to the alpha-chain of hemoglobin. The results also suggest that heme-heme interaction is different for oxygen than for carbon monoxide.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Carbon Monoxide / physiology*
  • Carboxyhemoglobin / analysis
  • Hemoglobins / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Mathematics
  • Oxygen / blood*


  • Hemoglobins
  • Carbon Monoxide
  • Carboxyhemoglobin
  • Oxygen