Hemoglobin heterogeneity under conditions of abnormal erythropoiesis.

Experiments on rats showed that changes in the hemoglobin profile during hypoxia are determined by switching of erythropoiesis from the "basic" to "emergency" mode. The "basic" mode of erythropoiesis is typical of the mature organism under normal conditions. The "reserve" or "emergency" mode is realized in fetuses, senile animals, and during hypoxia. This mode is characterized by production of large erythrocytes with high content of fetal hemoglobin.