Hypoxic incubation leads to concerted changes of carbonic anhydrase activity and 2.3 DPG concentration of chick embryo red cells.

Red cell carbonic anhydrase activity, 2.3 DPG concentration, and activities of three key enzymes controlling DPG metabolism (PK, PFK and DPGM) were measured in normoxic and hypoxic (incubation in 13.5% O2) chick embryos. In normoxia 2.3 DPG concentration and carbonic anhydrase activity begin to increase by the third week of incubation. Hypoxia induces a rise of 2.3 DPG concentration and carbonic anhydrase activity by Day 8 of development, i.e., 1 week earlier. Since during normal development chick embryos become hypoxic in the third week of incubation, the results suggest that PO2 has a controlling influence on the timing of differentiation events of definitive embryonic red cells.