Davis B M, Miller R K, Brent R L, Koszalka T R
Biol Neonate. 1978;33(1-2):43-54. doi: 10.1159/000241050.
The transfer of 14C-creatine to the rat fetus was studied following continuous i.v. infusion into the mother. In the presence of a relatively constant maternal plasma 14C-creatine concentration, creatine was accumulated by the chorioallantoic placenta and visceral yolk sac to concentrations higher than that found in maternal or fetal plasma. The ability of the extraembryonic membranes to accumulate creatine changed during gestation; nevertheless, these membranes concentrated creatine against a gradient throughout the period studied (14-22 days of gestation). Neither 14C-creatine nor 14C-urea were concentrated in the placentae or fetal plasma when compared to maternal plasma. Simultaneous infusion of beta-guanidinopropionic acid with 14C-creatine reduced both movement and accumulation of creatine into the fetoplacental unit. It is concluded that the accumulation of creatine by the chorioallantoic placenta and by the visceral yolk sac is an active process with creatine diffusing down its concentration gradient into the fetal circulation.
在对母体进行连续静脉输注后，研究了14C-肌酸向大鼠胎儿的转移情况。在母体血浆14C-肌酸浓度相对恒定的情况下，绒毛尿囊胎盘和内脏卵黄囊会积累肌酸，使其浓度高于母体或胎儿血浆中的浓度。胚外膜积累肌酸的能力在妊娠期会发生变化；然而，在整个研究期间（妊娠14 - 22天），这些膜都会逆浓度梯度浓缩肌酸。与母体血浆相比，胎盘或胎儿血浆中既不会浓缩14C-肌酸，也不会浓缩14C-尿素。同时输注β-胍基丙酸和14C-肌酸会减少肌酸向胎儿-胎盘单位的转运和积累。结论是，绒毛尿囊胎盘和内脏卵黄囊对肌酸的积累是一个主动过程，肌酸会顺着其浓度梯度扩散到胎儿循环中。
