Fetal substrate uptake during increased ovine fetal cortisol
concentration.
Ross, J., Milley.
Division of Neonatology, Department of Pediatrics, University of
Utah School of Medicine, Salt Lake City, Utah 84132
APStracts 3:0028E, 1996.
Corticosteroid administration adversely affects fetal growth and
consequently, unless metabolic rate increases (thereby increasing the
need for fetal metabolic substrates), reduces fetal need for
exogenous substrates. To find whether the uptake of all or only
certain metabolic substrates was affected by fetal hypercortisolemia,
we measured exogenous uptake of glucose, lactate, and [alpha]-amino
nitrogen during fetal hypercortisolemia in 7 late gestation sheep
fetuses. Hydrocortisone infusion increased fetal cortisol
concentrations from normal to values usually associated with late
gestation (4.3 +/- 0.9 vs. 72.5 +/- 5.0 ng/ml; P<0.001). In
association with increased fetal cortisol concentration, both fetal
metabolic rate and the uptakes of glucose and lactate remained
constant. The uptake of [alpha]-amino nitrogen containing substances,
however, fell (39.6 +/- 3.1 vs. 28.5 +/- 3.4 [mu]mol x kg-1 x min-1;
P<0.002) as did the proportion of metabolic rate (0.45 +/- 0.04
vs 0.32 +/- 0.04; P<0.002) that could be supported by metabolism
of these substances. The proportion of fetal metabolism that could be
supported by complete metabolism of all substrates taken up across
the placenta decreased (1.09 +/- 0.07 vs 0.95 +/- 0.06; P<0.02).
In conclusion, hypercortisolemia alters the composition of oxidative
substrates taken up by the sheep fetus and decreases total fetal
substrate uptake. These changes occur within hours of exposure to
increased cortisol concentration.
Received 31 July 1995; accepted in final form 19 January 1996.
APS Manuscript Number E354-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96