Gh and igf-i differentially increase protein synthesis in skeletal
muscle and jejunum of parenterally-fed rats.
Lo, Hui-Chen, and Denise M. Ney.
Department of Nutritional Sciences, University of Wisconsin
-Madison, Madison, Wisconsin 53706
APStracts 3:0147E, 1996.
GH and IGF-I selectively increase tissue mass. We compared the
fractional rate of protein synthesis (Ks) in skeletal muscle, jejunal
mucosa and muscularis, and liver to investigate the differential
effects of GH and IGF-I on tissue protein synthesis. Surgically
-stressed rats were maintained with hypocaloric total parenteral
nutrition (TPN) and given rhGH, rhIGF-I, rhGH+rhIGF-I (800 or 800 +
800 [mu]g/day) or TPN alone. After 3 days, a flooding dose of valine
(800 [mu]mole with 5.56 MBq L-3,4-3H-valine) was administered and
rats were killed 20 min later. Body weight gain, nitrogen retention,
and serum IGF-I concentrations confirmed that GH plus IGF-I
additively increased anabolism. Serum insulin concentrations were
significantly increased by GH and decreased by IGF-I. GH
significantly increased Ks in skeletal muscle and jejunal muscularis;
IGF-I significantly increased Ks in jejunal mucosa and muscularis;
and neither GH or IGF-I altered Ks in liver. GH and IGF-I
differentially increase tissue protein synthesis in vivo.
Received 12 March 1996; accepted in final form 12 July 1996.
APS Manuscript Number E127-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996