Fig. 4.

In vivo transplacental transfer of essential amino acids (EAAs). A: mole percent excess (MPE) ratios of stable isotope labeled leucine (Leu) and lysine (Lys) in maternal arterial blood after intravenous injection of a mixture of labeled EAAs to the pregnant baboon at GD 165 (n = 5). B: fetal vein/maternal artery (Fv/M) MPE ratios of nine EAAs in baboons (n = 5) and pregnant women (n = 5–7). Ile, isoleucine; Met, methionine; Phe, phenylalanine; Thr, threonine; His, histidine; Val, valine; Trp, tryptophan. C: Fv/M MPE ratios of nine EAAs in MNR baboons (n = 4) compared with controls (n = 5) at GD 165. Values are means ± SE. *P < 0.01.