Effect of hyperinsulinemia on amino acid utilization in the ovine fetus

Abstract

We studied the effect of an acute 4-h period of hyperinsulinemia (H) on net utilization rates (AAURnet) of 21 amino acids (AA) in 17 studies performed in 13 late-gestation fetal sheep by use of a novel fetal hyperinsulinemic-euglycemic-euaminoacidemic clamp. During H [84 ± 12 (SE) μU/ml H, 15 ± 2 μU/ml control (C), P < 0.00001], euglycemia was maintained by glucose clamp (19 ± 0.05 μmol/ml H, 1.19 ± 0.04 μmol/ml C), and euaminoacidemia (mean 4.1 ± 3.3% increase for all amino acid concentrations [AA], nonsignificantly different from zero) was maintained with a mixed amino acid solution adjusted to keep lysine concentration constant and other [AA] near C values. H produced a 63.7% increase in AAURnet (3.29 ± 0.66 μmol · min−1 · kg−1 H, 2.01 ± 0.55 μmol · min−1 · kg−1 C, P < 0.001), accounting for a 60.1% increase in fetal nitrogen uptake rate (2,064 ± 108 mg · day−1 · kg−1 H, 1,289 ± 73 mg · day−1 · kg−1 C, P < 0.001). Mean AA clearance rate (AAURnet/[AA]) increased by 64.5 ± 18.9% ( P < 0.001). Thus acute physiological H increases net amino acid and nitrogen utilization rates in the ovine fetus independent of plasma glucose and [AA].