Placental Transfer of Lactate, Glucose and 2-deoxyglucose in Control and Diabetic Wistar Rats

Placental transfer of lactate, glucose and 2-deoxyglucose was examined employing the in situ perfused placenta. Control and streptozotocin induced diabetic Wistar rats were infused with [U(14)C]-glucose and [(3)H]-2-deoxyglucose (2DG). The fetal side of the placenta was perfuseci with a cell free medium and glucose uptake was calculated in the adjacent fetuses. Despite the 5-fold higher maternal plasma glucose concentration in the diabetic dams the calculated fetal glucose metabolic index was not significantly different between the 2 groups. Placental blood flow was reduced in the diabetic animals compared with controls but reduction of transfer of [U(14)C]-glucose and [(3)H]-2-deoxyglucose and endogenously derived [(14)C]-Lactate to the fetal compartment, could not be accounted for by reduced placental blood flow alone. There was no significant net production or uptake of lactate into the perfusion medium that had perfused the fetal side of the placenta in either group. The plasma lactate levels in the fetuses adjacent to the perfused placenta were found to be higher than in the maternal plasma and significantly higher in the fetuses of the diabetic group compared with control group. In this model the in situ perfused placenta does not secrete significant quantities of lactate into the fetal compartment in either the control or diabetic group.