Maternal and Fetal Plasma Amino Acid Concentrations During Gestation and in Retarded Fetal Growth

Placental transfer and fetal uptake of amino acids in the pregnant ewe

“…The plasma amino acid values in the pregnant ewe were lower than in the non pregnant sheep (LEIBHOLZ [20]) s might be expected from the fall in total <%-amino nitrogen observed by CURET et al [4] during gestation in the ewe. The general pattern and level of the amino acid concentrations in the maternal plasma were similar to that found in the human subject (YouNG and PRENTON [40]) and in the guinea pig (HiLL and YOUNG [12]); the high glycine is characteristic of other ruminants, while the branched chain amino acids, valine, isoleucine and leucine are low in comparison with the cow and the goat (VERBEKE and PEETERS [35], MEPHAM and LINZELL [26]). LEIBHOLZ'S [21] finding of l and 3 methylhistine in the sheep plasma was confirmed for both mother and fetus.…”

The Metabolic and Endocrine Milieu of the Human Fetus and Mother at 18-21 Weeks of Gestation. I. Plasma Amino Acid Concentrations

“…No human data are available on uptake of AA and information on the circulating concentrations of AA during early gestation is scarce (3,10,12). Moreover, the usefulness of the available data is limited because of the circumstances of blood collection.…”

“…Moreover, the usefulness of the available data is limited because of the circumstances of blood collection. Thus, earlier studies were performed on fetuses at hysterotomy after placental separation and under maternal anaesthesia (3,12), while only one fetal vessel was sampled in a more recent study in which blood samples were obtained by fetoscopy (10).…”

Taurine Transport in the in Vitro Perfused Human Placenta

“…35-1.50. No studies of taurine transfer in the intact human placenta have been performed other than measuring the concentration of taurine in the maternal serum and cord blood either at fetoscopy (26) (fetallmaternal taurine concentration ratio: 3.65) or at the time of delivery (27,28) (fetal/maternal taurine concentration ratios: 3.14, 2.25). However, taurine transport has been studied in placental brush-border membrane vesicles revealing an active carrier mechanism (2 1).…”