Effects of circulating igf-i on glucose and amino acid kinetics in
the ovine fetus.
Liechty, Edward A., David W. Boyle, Helen Moorehead, Wei-Hua Lee,
Ronald R. Bowsher, and Scott C. Denne.
Department of Pediatrics, Indiana University School of Medicine and
Eli Lilly Research Laboratories, Indianapolis, IN 26202
APStracts 3:0060E, 1996.
To investigate the role of IGF-I in the regulation of fetal
metabolism, the kinetics of leucine, phenylalanine and glucose were
assessed in the chronically catheterized ovine fetus (0.85 gestation)
before and during infusion of rhIGF-I. Substrate kinetics were
determined by tracer dilution. rhIGF-I was infused at 6.7 nmol/kg
fetus/hour. Fetal insulin and growth hormone concentrations were
significantly decreased by 50% during rhIGF-I infusion. Net umbilical
glucose uptake was unchanged and glucose rate of appearance increased
in the fed state only. There were no changes in the net umbilical
uptakes of leucine or phenylalanine, but the rates of appearance of
both declined during rhIGF-I infusion, indicative of decreased fetal
protein breakdown (RaLeu 45.4 +/- 1.40 to 40+/-1.4 [mu]mols/minute in
the fed state, 43+/-1.5 to 37+/-1.5 in the fasted state; RaPhe
10.7+/-0.3 to 10.4+/-0.3 in the fed state and from 10.7+/-0.3 to
9.8+/-0.3 in the fasted). Leucine oxidation was also decreased
(8.90+/-0.76 to 6.52+/-0.81,p=0.025), more so in the fasted than the
fed state. These results indicate a significant antiproteolytic
endocrine effect for IGF-I in the late gestation mammalian fetus.
Received 16 November 1995; accepted in final form 28 February
1996.
APS Manuscript Number E544-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96