Growth hormone (gh)-binding protein enhances gh activity in
vivo.
D., Turyn, Dominici, F. P., Sotelo, A. I. and Bartke, A.
Instituto de Qu[acute]imica y Fisicoqu[acute]imica Biol[acute]ogica
(UBA-CONICET), Facultad de Farmacia y Bioqu[acute]imica, Buenos
Aires, Argentina; Department of Physiology, School of Medicine,
Southern Illinois University, Carbondale, IL, 62901-6512 USA.
APStracts 4:0125E, 1997.
_The decay curve of labeled GH in the plasma followed a three
compartment model and could be described by the equation:
Concentration = Ae-[alpha]t + Be-[beta]t + C e-_t. When 125I-oPRL was
injected, the decay curve could be described by the equation:
Concentration = Ae-[alpha]t + C e-_t. Formation of [125I-bGH-GHBP]
complexes with somatogenic characteristics was demonstrated in the
serum of both normal and GH transgenic mice. In contrast, 125I-oPRL
was unable to form complexes of this type in any of the mice studied.
Receptor mediated liver uptake was found to be faster for PRL than for
GH (5-6 min. vs. 15-20 min.). Liver uptake of radioactivity was
significantly lower for PRL than for GH (liver to blood (L/B) ratio
of 1.7 +/- 0.3 at 6 min. vs. L/B ratio of 3.7 +/- 0.6 at 20 min.,
respectively). The presence of binding proteins for GH substantially
reduces the clearance of this hormone and consequently increases the
liver uptake of GH (mediated by GH-receptors). This suggests that
GHBPs act to increase the biological activity of GH in vivo.
Prolactin (PRL), PRL-binding protein, GH decay curves, PRL decay
curves, Receptors.
Received 1997 March 18; accepted in final form 1997 May 20
APS Manuscript Number E122-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 11 June 1997