The effect of maternal hypoaminoacidaemia on placental uptake and transport of amino acids in pregnant sheep

We developed a model of maternal hyperglycaemia with secondary hyperinsulin aemia and hypoaminoacidaemia in pregnant sheep (H) to determine the effect of these conditions on uterine, uteroplacental and fetal amino-acid uptake rates and fetal amino-acid concentrations [AA]. Results were compared with normal pregnant ewes (C). Plasma glucose concentrations were greater in H v ersus C animals: 7.7 +/- 0.3 versus 3.9 +/- 0.1 mmol/l maternal, P<0.005; 2 .6 +/- 0.1 versus 1.1 +/- 0.1 mmol/l fetal, P<0.005. Maternal insulin conce ntrations [1] were greater in the H group (132 +/- 30 H versus 31 +/- 5 C m uU/ml, P<0.005); fetal [I] were not different (15 +/- 2 H versus 16 +/- 2 C <mu>U/mL). Maternal [AA] were lower in H than C groups except for SER (P=n s) and GLY (approx twofold higher, P<0.01). Uterine, uteroplacental and fet al uptake rates of several AA, particularly the branch chain AA, were lower in H than C animals, producing lower total fetal nitrogen uptake rates (27 0 +/- 64 mg N/kg fetus/day H, 696 +/- 75 mg N/kg fetus/day C, P=0.001) and lower fetal plasma concentrations for the branch chain AA. Most fetal [AA], however, remained at control values, which could occur by relative increas e in fetal amino-acid production and/or decrease in utilization, but not by increased uteroplacental transport rates. (C) 2001 Harcourt Publishers Ltd .