The Adaptation of the Fetal Red Cells of Newborn Lambs to Extrauterine Life: The Role of 2,3-Diphosphoglycerate and Adult Hemoglobin

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Abstract
Extract: The purpose of this study was to determine the interrelationship of the rise and fall of 2,3-diphosphoglycerate (DPG) with the increase in adult hemoglobin and the decrease in red cell oxygen hemoglobin affinity after birth in normal lambs. It was found that the mean maximum DPG level was 26.71 ± 4.98 mol/g Hb at 7.5 ± 1.1 days. At the same time the mean P50 and adult hemoglobin level was 27.0 ± 1.4 mm Hg and 31.1 ± 11.1%, respectively. In the individual lambs, the level of their maximum DPG correlated inversely with the amount of adult hemoglobin (r – 0.77, P < 0.05). Once the DPG began to decrease, there was an inverse correlation between the DPG and the adult hemoglobin present in the red cell (r = 0.68, P < 0.001). It appeared that the rise in DPG postanatally is only a compensatory mechanism until an adequate amount of adult hemoglobin is present. This fact was borne out by the second part of the study in which exchange transfusions with adult red cells were performed on five newborn lambs during the first 24 hr after birth and aborted the rise in DPG. Speculation: The adaptation from the in utero to the extrauterine environment requires a rapid reduction in red cell oxygen affinity. The decrease in oxygen affinity is achieved by a transitory postnatal increase in intraerythrocyte DPG.

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