title: Transplacental supply of mannose and inositol in uncomplicated pregnancies using stable isotopes.
abstract: OBJECTIVE
  The aim of this study was to determine relative contributions of transplacental flux vs. fetal production for inositol and mannose in normal term pregnancies.
  
  
  METHODS
  Seven term uncomplicated pregnancies undergoing cesarean section were infused with (13)C- and (2)H-labeled isotopes of glucose, inositol, and mannose until a steady state was achieved. Maternal and fetal concentrations of labeled and unlabeled glucose, mannose, and inositol were measured using gas chromatography/mass spectroscopy. The fetomaternal molar percentage excess ratio was calculated for each glucose, mannose, and inositol.
  
  
  RESULTS
  The fetomaternal molar percentage excess ratio of mannose in the fetal artery (F(artery)/M) was 0.99 [97.5% confidence interval (CI), 0.91-1.07] and in the fetal vein (F(vein)/M), 1.02 (97.5% CI, 0.95-1.10). Both were not significantly different from 1.0, consistent with transplacental supply. The fetomaternal ratios for glucose were similar to mannose (fetal artery, 0.95; 97.5% CI, 0.84-1.15; and fetal vein, 0.96; 97.5% CI, 0.85-1.07). The fetomaternal ratio for inositol was significantly less than 1.0 (fetal artery, 0.08; 97.5% CI, 0.05-0.12; fetal vein, 0.12; 97.5% CI, 0.06-0.18), indicating little transplacental flux and significant fetal production.
  
  
  CONCLUSIONS
  In normal term pregnancies, fetal mannose and glucose concentrations are dependent upon maternal transplacental supply. Fetal inositol is not dependent upon transplacental supply.
authors.affiliation: Department of Obstetrics, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA. Barton.staat@us.af.mil
authors.forename: Barton C
authors.initials: BC
authors.lastname: Staat
authors.forename: Henry L
authors.initials: HL
authors.lastname: Galan
authors.forename: Jeri E F
authors.initials: JE
authors.lastname: Harwood
authors.forename: Gene
authors.initials: G
authors.lastname: Lee
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Marconi
authors.forename: Cinzia L
authors.initials: CL
authors.lastname: Paolini
authors.forename: Alex
authors.initials: A
authors.lastname: Cheung
authors.forename: Frederick C
authors.initials: FC
authors.lastname: Battaglia
mesh_terms: D000328:Adult; D002247:Carbon Isotopes; D002585:Cesarean Section; D005260:Female; D006801:Humans; D006859:Hydrogen; D007231:Infant, Newborn; D007294:Inositol / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D007553:Isotope Labeling / Q000379:methods*; D008297:Male; D008358:Mannose / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D008431:Maternal-Fetal Exchange / Q000502:physiology; D010920:Placenta / Q000098:blood supply; D021041:Placental Circulation / Q000502:physiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood
chemical_list: D002247:Carbon Isotopes; D007294:Inositol; D006859:Hydrogen; D008358:Mannose