Regulation of red cell DPG metabolism in fetuses and adults.

We have compared red cell levels of 2,3-DPG in relation to the activities of certain glycolytic enzymes (DPGM, PK, PFK) between fetuses and adults in various rodents in order to find out the possible causes of the low intraerythrocytic concentration of 2,3-DPG in the fetal period. It was concluded that, in all species studied, 2,3-DPG synthesis was limited by a high activity of PK in fetal red cells. In addition, in species of the suborder Myomorpha, the activity of DPGM was lower in fetal red cells than in adults. In particular, the 2,3-DPG deficient fetal rat red cells completely lacked DPGM activity.