Perinatal changes of 2,3-diphosphoglycerate and oxygen affinity in mammals not having fetal type hemoglobins

The interrelationship of 2,3-diphosphoglycerate (2,3-DPG) and P50 levels during the fetal and postnatal life were determined in two mammalian species which do not have a switchover of hemoglobin type at the end of their fetal development. In the guinea pig and rabbit, the 2,3-DPG levels remain low during fetal life and increase only after birth remaining elevated throughout adult life. The adult levels were reached at 2 days of age in the guinea pig and the 20th day in rabbit. Fetal P50 values increased only after birth, paralleling the rise in the 2,3-DPG. The rapidity of the postnatal rise in 2,3-DPG and decrease in P50 appears related to the maturity of the newborn animal at birth in these species.