Studies of animal hemoglobins III. The possible role of intercellular inorganic phosphate on the oxygen equilibrium of the hemoglobin in the developing chicken

Abstract

The hemoglobin of red cell hemolysates of chicken embryos and chickens after hatching have been reinvestigated using starch-gel electrophoresis and O₂ equilibrium measurements. Thee hemoglobin components were found, namely the major and minor hemoglobin fractions also present in the adult chicken red cell hemolysates and a slow-moving fraction, which disappeared gradually from the blood after hatching. The electrophoretic mobility of the minor hemoglobin fraction in embryonic red cell hemolysates was slower than that of the fractions observed in 1-day-old chick and in adult chicken hemolysates, and was the same as that produced by preincubation of these hemolysates with 0.2 M phospahte buffers. It was also observed that the erythrocytic inorganic phosphate level was several times higher in the newborn chicken than in the adult fowl; the decrease in phosphate level after hatching coincides with the decrease in O₂ affinity of total blood samples as observed by others. The equilibrium of the total red cell hemolysate of a 1-day-old chicken with O₂ showed a higher O₂ affinity at low phosphate molarity, which decreased with increased phosphate concentration in a similar ways as observed for adult red cell hemolysates being pre-exposed to phosphate. The possible role of the phospahte content of the red cell in the regulation of the O₂ affinity of the chicken hemoglobin during development has been discussed.