Umbilical amino acid uptake at increasing maternal amino acid concentrations: effect of a maternal amino acid infusate.
OBJECTIVE
Our purpose was to establish whether, in normal human pregnancies, the maternal intravenous infusion of amino acids can increase fetal amino acid uptake and amino acid concentrations.


METHODS
Twenty-six normal pregnancies were studied at the time of cesarean delivery (38-40 weeks' gestation). In 10 cases an amino acid formulation (Freamine 8.5% III, Baxter) was infused into a maternal vein before cesarean delivery. Maternal blood samples were obtained during the course of the study. Umbilical venous and arterial samples were obtained from the clamped segment of the cord. There were no differences between the 2 groups for fetal and placental weights and for fetal oxygenation and acid-base balance.


RESULTS
Maternal amino acid concentrations increased significantly in the group receiving infusions. Significant increases in umbilical venous concentrations were observed for most amino acids, except for histidine and threonine. The amino acid umbilical arteriovenous differences per mole of oxygen (AA/O(2) ratio) increased significantly for leucine, isoleucine, valine, methionine, phenylalanine, arginine, glycine, serine, alanine, and proline. There were no significant increases for lysine, histidine, and threonine.


CONCLUSIONS
An increase in maternal concentrations leads to an increase in the delivery of most amino acids to the fetus.
Ronzoni
S
S
Department of Obstetrics and Gynecology, San Paolo Institute of Biomedical Sciences, University of Milan, Italy.
Marconi
A M
AM
Cetin
I
I
Paolini
C L
CL
Teng
C
C
Pardi
G
G
Battaglia
F C
FC
D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage* / Q000097:blood*; D001158:Arteries; D004573:Electrolytes; D005260:Female; D005947:Glucose; D006801:Humans; D008431:Maternal-Fetal Exchange; D057947:Parenteral Nutrition Solutions; D011247:Pregnancy; D012996:Solutions; D014469:Umbilical Arteries; D014471:Umbilical Veins
D000596:Amino Acids; D004573:Electrolytes; D057947:Parenteral Nutrition Solutions; D012996:Solutions; C545824:amino-acid, glucose, and electrolyte solution; D005947:Glucose