Glucose and amino acid kinetic response to graded infusion of rhIGF-I in the late gestation ovine fetus

Edward A. Liechty, David W. Boyle, Helen Moorehead, Wei Hua Lee, Xian Lin Yang, Scott C. Denne

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Insulin-like growth factor I (IGF-I) has anabolic effects and is thought to be important in fetal development. The present study was designed to determine the dose response of recombinant human (rh) IGF-I on ovine fetal glucose and amino acid kinetics. Chronically catheterized fetal lambs were studied at 122-127 days gestation. The kinetics of leucine, phenylalanine, and glucose were measured before and during the infusion of rhIGF-I. rhIGF-I was infused into the fetal inferior vena cava at low, medium, or high rates (9.9, 20.1, or 40.2 nmol/h, respectively). A stepwise increase in serum IGF-I was achieved (164 ± 3, 222 ± 7, and 275 ± 5 ng/ml). Insulin concentrations were decreased at the medium and high rhIGF doses. The rate of appearance (R(a)) of leucine and phenylalanine and leucine oxidation decreased. Phenylalanine appearance from protein breakdown was decreased, with a maximal suppression of 30% observed at the highest rate of infusion. Glucose R(a) was increased at the medium and high doses; other aspects of glucose metabolism were unchanged. The change in both glucose R(a) and suppression of proteolysis was significantly correlated to the rhIGF-I infusion rate. It is concluded that rhIGF-I exerts dose-related effects in the ovine fetus, increasing fetoplacental glucose turnover and causing significant suppression of both proteolysis and amino acid oxidation.

Original languageEnglish (US)
Pages (from-to)E537-E543
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number3 40-3
StatePublished - Sep 1999


  • Leucine
  • Phenylalanine
  • Stable isotopes
  • Tyrosine

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Biochemistry
  • Physiology (medical)

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