Lactate transport at the uteroplacental unit- A theoretical study

Deciphering the lactate transport within the uteroplacental unit should be aided by a theoretical model in light of the insurmountable difficulties involved with in-vivo relevant measurements. Here we formulate a boundary value problem that predicts the direction and extent of lactate fluxes within the human placenta under various physiological conditions. It accounts for metabolic processes within the placenta and transporters activity at the two membranes that confine the terminal villi. Lactate concentration inside the terminal villi and its fluxes at the membranes are being computed. Under normal conditions lactate flux from fetal arterioles to the placenta surpasses the flux to the fetus via the umbilical vein. Within the placenta, it adds to the lactate that originates in the glycolysis, some of it degrades to pyruvate and surpluses are delivered to the maternal circulation. The apparent permeabilities of the placental membranes with respect to lactate as well as the specific characterizations of the placental lactate production, hitherto unknown, are being estimated. We determine the range of parameter values that induce sustainable, healthy fetal lactate levels and demonstrate the versatility of lactate exchange between the placenta and the fetus by computing the effect of extreme conditions (e.g., cesarean section, intrauterine growth restriction) on lactate fluxes.