Lasunción M A, Lorenzo J, Palacin M, Herrera E
Biol Neonate. 1987;51(2):86-93. doi: 10.1159/000242637.
Current knowledge of the modulation of maternal-fetal transfer of metabolites is reviewed and new data on the actual placental transport of D-glucose, L-alanine and glycerol in the rat are presented. Twenty-one day pregnant rats were infused with the 14C-labelled substrates throughout the left uterine artery. Radioactivity appearing in fetuses was corrected by the specific dilution of the tracer at maternal arterial plasma and the uterine artery blood flow to estimate placental transfer. This parameter appeared to be 127 mumol X kg-1 fetal b.w. X min-1 for D-glucose, 23 for L-alanine, and 1 for glycerol--values which are much higher than those described for larger species. There is a parallelism between the magnitude of transfer to fetus and arterial concentration in mother for each studied metabolite and actually variations in their plasmatic levels affect this transport process. This is clearly seen in the case of glucose where placental transfer is reduced during fasting hypoglycemia and greatly increased in diabetes. Placental transfer of L-alanine and blood flow to the placenta were reduced in both 48-hour starved and streptozotocin-induced diabetic late pregnant rats. Results show the main role of maternal nutrient concentration as a modulator of their transfer to fetus, the deleterious effect of reductions of uterine blood flow on placental transport of amino acids as well as the small placental transfer of glycerol as compared to either glucose or alanine.
本文综述了目前关于代谢物母胎转运调节的知识，并展示了大鼠中D-葡萄糖、L-丙氨酸和甘油实际胎盘转运的新数据。对21天妊娠的大鼠通过左子宫动脉持续输注14C标记的底物。通过母体动脉血浆中示踪剂的特异性稀释和子宫动脉血流量对胎儿中出现的放射性进行校正，以估计胎盘转运。该参数对于D-葡萄糖似乎为127 μmol·kg-1胎儿体重·min-1，对于L-丙氨酸为23，对于甘油为1——这些值远高于较大物种所描述的值。对于每种研究的代谢物，向胎儿的转运量与母体动脉浓度之间存在平行关系，并且它们血浆水平的实际变化会影响这种转运过程。这在葡萄糖的情况下很明显，在空腹低血糖期间胎盘转运减少，而在糖尿病中则大大增加。在饥饿48小时和链脲佐菌素诱导的糖尿病晚期妊娠大鼠中，L-丙氨酸的胎盘转运和胎盘血流量均减少。结果表明母体营养物质浓度作为其向胎儿转运的调节因子的主要作用、子宫血流量减少对氨基酸胎盘转运的有害影响以及与葡萄糖或丙氨酸相比甘油的胎盘转运量较小。
