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NA Noble, CA Jansen, PW Nathanielsz and KR Tanaka
The tenfold increase in red cell 2,3-diphosphoglycerate (DPG) concentration
that occurs during the first 5 days of life in lambs is an important
adaptation to extrauterine life. In lambs, DPG reduces hemoglobin oxygen
affinity by the Bohr effect. Our data on 10 neonatal lambs suggest that the
biochemical mechanism underlying this DPG increase involves the following:
(1) a rise in plasma glucose from 40 to 100 mg/dl in the first 48 hr of
life, which allows for increased glucose consumption in the highly
glucose-permeable neonatal RBC; (2) a transitory rise in blood pH begins at
birth, peaks at about 20 hr, and falls slightly; (3) the pH increase
coincides with a threefold increase in RBC fructose-1,6-diphosphate (FDP)
concentration due, we believe, to pH activation of phosphofructokinase; (4)
glycolytic intermediates after the glyceraldehyde-3-phosphate dehydrogenase
(GAPD) step do not rise in the first 24 hr of life, possibly due to
insufficient inorganic phosphate (Pi), a substrate of GAPD; (5) plasma Pi
increases from about 7 mg/dl at birth to 11 mg/dl at 72 hr, activates the
GAPD, and FDP levels decline; and (6) the in vitro activity of the DPG
synthetic enzyme, DPG mutase, is increased 12-fold in neonatal compared to
adult RBC. We conclude that the postnatal rise in DPG is explained at least
in part by the sequential effects of these metabolic changes.
This article has been cited by other articles:
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| Copyright © 1983 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
