Oxygen affinity of blood of adult domestic chicken and red jungle fowl.

Respiratory properties of blood from adult domestic chicken (White Leghorn) and red jungle fowl (Gallus gallus, ancestor of domestic breeds) at 41 degrees C were investigated. Oxygen affinity was the same in blood of chicken and jungle fowl (P0.5 46.7 Torr at pH 7.5, 41 degrees C, PCO2 about 30 Torr). The Hill coefficient, nH, increased from 2 at oxygen saturation 0.1 to a maximum of 4.11 at saturation 0.8. Leghorn fixed acid and CO2 Bohr coefficients were -0.51 and -0.53, with little variation over the saturation range 0.15-0.95, indicating negligible specific CO2 effect. An nH value of greater than 4 may indicate polymerization of deoxyhemoglobin, comparable to that which occurs in sickle cell hemoglobin. A biphasic equilibrium curve shape (hump at the low end of the oxygen equilibrium curve) was noted in blood having some degree of hemolysis. Factors that may have contributed to the differences between previous investigations of chicken oxygen affinity are discussed.