Comparison of 2,3-diphosphoglycerate metabolism between fetal and postnatal pig red cells.

A four-fold increase in red blood cell 2,3-diphosphoglycerate (DPG) levels occurs within 1-2 weeks after birth resulting in a decrease in oxygen affinity in the newborn pig. In this study, we found that although newborn pig red blood cells seem to be equally capable of net DPG synthesis as adult pig cells when challenged by a mixture of inosine, pyruvate and phosphate, the cells from newborns degrade DPG much faster than do cells from adults. As a result, DPG levels in the newborn's cells do not seem to increase in comparison to the adult's cells. Using a density centrifugation technique, it was found that the postnatal cells initially entering the circulation have a relatively low rather than high DPG content. However, DPG content quickly increases as they age. These findings suggest that the rapid rise of DPG seen in the growing piglet is brought about in part (a) by an elimination of the fetal cells with low DPG, and (b) by an emergence of postnatal cells having the capacity to augment their DPG content while in circulation.