Crandell S S, Palma P A, Morriss F H
Am J Physiol. 1983 Jun;244(6):R882-7. doi: 10.1152/ajpregu.1983.244.6.R882.
Umbilical glucose and lactate extractions were determined in previously instrumented pregnant ewes into some of which D-glucose was infused to produce graded levels of maternal hyperglycemia as great as 20 mM. While fetal arterial glucose concentration continued to increase linearly as a function of maternal arterial glucose concentration during maternal hyperglycemia, the umbilical venoarterial difference in blood glucose concentration did not, and umbilical glucose extraction approached a plateau at approximately 0.063 mmol X min-1 X kg fetus-1 at maternal glucose concentrations greater than approximately 8 mM. The observed plateau in glucose extraction is consistent with saturation at high maternal glucose concentrations of the carrier mechanism for transport of glucose from the maternal to the fetal aspects of the trophoblast. The observed value of the plateau in umbilical extraction of glucose is slightly less than the maximum extraction predicted from previously published equations for this species, but the maternal blood glucose concentration at which the observed maximum occurred agrees closely with the value predicted by those equations. Umbilical lactate extraction, 0.031 +/- 0.021 mmol X min-1 X kg fetus-1, was independent of maternal arterial blood glucose and lactate concentrations and was independent of umbilical glucose extraction.
在先前已植入仪器的怀孕母羊中测定脐部葡萄糖和乳酸的摄取量，其中部分母羊输注D-葡萄糖以产生高达20 mM的不同程度的母体高血糖。在母体高血糖期间，虽然胎儿动脉葡萄糖浓度继续随母体动脉葡萄糖浓度呈线性增加，但脐静脉-动脉血糖浓度差并未如此，并且在母体葡萄糖浓度大于约8 mM时，脐部葡萄糖摄取量在约0.063 mmol·min⁻¹·kg胎儿⁻¹处接近平台期。观察到的葡萄糖摄取平台期与滋养层从母体到胎儿一侧转运葡萄糖的载体机制在高母体葡萄糖浓度下的饱和一致。观察到的脐部葡萄糖摄取平台期的值略低于根据该物种先前发表的方程式预测的最大摄取量，但观察到的最大值出现时的母体血糖浓度与那些方程式预测的值非常接近。脐部乳酸摄取量为0.031±0.021 mmol·min⁻¹·kg胎儿⁻¹，与母体动脉血糖和乳酸浓度无关，也与脐部葡萄糖摄取无关。
