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.

中文翻译：

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子宫胎盘单位的乳酸运移-理论研究

鉴于与体内相关测量所涉及的不可克服的困难，应该借助理论模型来帮助阐明子宫胎盘单位内的乳酸运输。在这里，我们提出了一个边界值问题，该问题可预测各种生理条件下人胎盘中乳酸通量的方向和范围。它解释了胎盘内的新陈代谢过程以及限制末端绒毛的两个膜上转运蛋白的活性。正在计算末端绒毛内部的乳酸浓度及其在膜上的通量。在正常情况下，从胎儿小动脉到胎盘的乳酸通量超过通过脐静脉到达胎儿的通量。在胎盘内，它会增加源自糖酵解的乳酸，其中一些会降解为丙酮酸，而多余的则会进入孕产妇循环。迄今为止，尚不清楚胎盘膜相对于乳酸的表观渗透性以及胎盘乳酸产生的具体特征。我们确定了可诱导可持续，健康的胎儿乳酸水平的参数值范围，并通过计算极端条件（例如剖宫产，子宫内生长受限）对乳酸通量的影响来证明胎盘与胎儿之间乳酸交换的多功能性。