Diabetes, Vol 39, Issue 3 276-282, Copyright © 1990 by American Diabetes Association
Effects of maternal diabetes on placental transfer of glucose in rats
CR Thomas, GL Eriksson and UJ Eriksson
Division of Medicine, United Medical School of Guy's Hospital, London, United Kingdom.
In situ perfusion of the fetal side of the anesthetized rat placenta was
used to monitor glucose fluxes in nondiabetic, streptozocin-induced
diabetic (STZ-D), acutely hyperglycemic nondiabetic, and acutely
normoglycemic STZ-D rats. STZ-D resulted in increased accumulation of
glucose in the perfusate during a single passage through the fetal
vasculature compared with nondiabetic rats, and this increase was
maintained in normoglycemic STZ-D rats, indicating glucose release from
placental stores. The fractional clearance of 3-O-[14C]methylglucose, a
nonmetabolizable glucose analogue, across the placenta was decreased in
both STZ-D groups compared with nondiabetic rats but unchanged in
hyperglycemic nondiabetic rats, implying a reduction in glucose
transporters in diabetic placentas. The difference between the transfer of
D-[3H]glucose and 3-O-[14C]methylglucose indicated that 17% of the glucose
was retained while traversing the placenta of nondiabetic rats, whereas a
smaller percentage (8%) but a larger absolute amount (9 vs. 6 mumol/h) of
glucose was retained by the placentas of the severely STZ-D rats. This
retention was markedly enhanced in hyperglycemic nondiabetic rats and STZ-D
rats when rendered normoglycemic. The net accumulation of perfusate glucose
was less than that predicted from radiolabeled transfer data, indicating
that glucose is also back transferred from the perfusate to the mother's
placenta. We conclude that maternal diabetes markedly affects placental
glucose flux.