Kyuma M
Nihon Sanka Fujinka Gakkai Zasshi. 1984 Mar;36(3):405-14.
A new technique for injecting tracer into the rat fetus in utero, intraperitoneally, was employed to characterize the amino acid exchange at the fetal surface of the trophoblast and to study the transplacental amino acid transfer. Calculation of tissue fluid distribution via 3H-inulin space made it possible to estimate the placental intracellular amino acid concentration on the basis of the cord and maternal plasma concentration. The fetal plasma free amino acid was taken up at a considerable rate by the fetal surface of the placenta in umbilical circulation. The amino acid from fetal plasma was utilized for the protein synthesis and deamination in the placenta. It was speculated that the amino acid transfer at the fetal surface of the placenta was carrier-mediated facilitated diffusion, not simple diffusion, on the basis of the data showing the stereospecificity for the isomers. From these results it was considered that the fetal, not maternal, plasma free amino acid concentration greatly influenced the fetal amino acid net uptake.
采用一种新的经腹腔向子宫内大鼠胎儿注射示踪剂的技术，以表征滋养层胎儿表面的氨基酸交换，并研究经胎盘的氨基酸转运。通过3H-菊粉空间计算组织液分布，使得根据脐带和母体血浆浓度估算胎盘细胞内氨基酸浓度成为可能。在脐循环中，胎儿血浆中的游离氨基酸以相当高的速率被胎盘的胎儿表面摄取。来自胎儿血浆的氨基酸被用于胎盘内的蛋白质合成和脱氨基作用。根据显示对异构体具有立体特异性的数据推测，胎盘胎儿表面的氨基酸转运是载体介导的易化扩散，而非简单扩散。从这些结果可以认为，胎儿而非母体的血浆游离氨基酸浓度对胎儿氨基酸净摄取有很大影响。
