The transplacental transport of essential amino acids in uncomplicated human pregnancies.
OBJECTIVE
The purpose of this study was to assess the placental transport of the essential amino acids (EAAs) in normal pregnancies.


METHODS
Nine ((13)C or (2)H) EAAs were infused simultaneously as a bolus into the maternal circulation of 12 patients with uncomplicated pregnancy before cesarean delivery. Maternal samples were collected before and after the bolus; umbilical blood was collected at delivery. The fetal/maternal molar percent enrichment for each EAA was calculated for both the umbilical vein and artery. Plasma amino acids enrichments were analyzed by gas chromatography mass spectrometry and concentrations by high performance liquid chromatography. Data were analyzed with paired and unpaired t-test.


RESULTS
The umbilical arterial enrichments were significantly lower than the venous. Fetal/maternal ratios for leucine, isoleucine, methionine, and phenylalanine were > 0.80, with no significant differences among their molar percent enrichment ratios, whereas fetal/maternal ratios of the other 5 EAAs were significantly lower (< 0.60).


CONCLUSIONS
The EAAs showed significant umbilical uptake and striking differences in their transport rates in vivo.
Galan
Henry L
HL
Section of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora, CO 80045, USA. henry.galan@uchsc.edu
Marconi
Anna Maria
AM
Paolini
Cinzia L
CL
Cheung
Alex
A
Battaglia
Frederick C
FC
D000328:Adult; D000601:Amino Acids, Essential / Q000097:blood / Q000378:metabolism*; D001692:Biological Transport; D001724:Birth Weight; D002585:Cesarean Section; D017218:Cordocentesis; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy / Q000378:metabolism*; D012044:Regression Analysis; D014469:Umbilical Arteries; D014471:Umbilical Veins
D000601:Amino Acids, Essential