AJP - Endocrinology and Metabolism, Vol 270, Issue 4 E545-E551, Copyright © 1996 by American Physiological Society
IGF-I alters skeletal muscle substrate metabolism and blunts recovery from insulin-induced hypoglycemia
M. A. Hussain, O. Schmitz, J. S. Christiansen, N. J. Christensen, K. G. Alberti and E. R. Froesch
Department of Internal Medicine, University Hospital of Zurich, Switzerland.
Eight healthy subjects were treated with saline or insulin-like growth
factor I (IGF-I, 10 micrograms.kg-1.h-1 sc) for 3 days in a crossover
randomized fashion. Substrate balances across the forearm skeletal vascular
bed were determined in the postabsorptive state and during a
hyperinsulinemic euglycemic clamp. In the basal state, net forearm uptake
of free fatty acids and ketone bodies was increased during IGF-I
administration in the face of elevated plasma levels of these substrates,
whereas basal glucose levels and forearm glucose balance were unchanged.
However, whole body and net forearm glucose uptakes were more markedly
stimulated by insulin (+20 and +8%, respectively) in the IGF-I period.
Additionally, counterregulatory hormone responses were examined during
insulin-induced stepwise hypoglycemia. Responses of growth hormone and
glucagon were blunted, those of cortisol and epinephrine were more marked,
and that of norepineprine was unchanged during IGF-I administration. These
changes were accompanied with delayed recovery from hypoglycemia.
