Abstract
Experiments were carried out in anaesthetized pregnant guinea-pigs. Following the maternal injection of a bolus containing 14C-hexose and 3H2O, blood was sampled from the fetal umbilical vein during a single circulatory transit. A placental transfer index was calculated from the ratio of the tracers in the fetal whole blood divided by that in maternal plasma. The transfer index for D-glucose, 0.66±0.03 (SEM), greatly exceeded that for L-glucose, 0.013±0.004. Elevation of the maternal plasma D-glucose concentration, with unlabelled D-glucose, resulted in saturation of D-glucose transfer with an apparent K of 1.2x10-2 mol/l mean maternal plasma D-glucose. Phlorizin at maternal plasma concentrations of approximately 10-3 mol/l inhibited D-glucose transfer by 40%. Phloretin did not affect D-glucose transfer at levels estimated to be 10-4 mol/l. Specificity studies with substituted D-glucose analogues showed that α-methyl-D-glucoside is not transported by a facilitated pathway; 2-deoxy-D-glucose and 3-O-methyl-D-glucose share the D-glucose carrier and D-galactose has a partial affinity for the D-glucose carrier.
Original language | English (US) |
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Pages (from-to) | 415-426 |
Number of pages | 12 |
Journal | Journal of Developmental Physiology |
Volume | 1 |
Issue number | 6 |
State | Published - 1979 |
ASJC Scopus subject areas
- Developmental Biology
- Physiology