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The effects of infusion of insulinlike growth factor (IGF) I, IGF-II, and insulin on glucose and protein metabolism in fasted lambs.
J Clin Invest. 1991 Aug; 88(2):614-22.JCI

Abstract

In vivo effects of 300-min infusions of recombinant insulinlike growth factor I (IGF-I) and IGF-II on glucose and protein metabolism have been investigated in awake, fasted lambs. Two doses of recombinant human (rh) IGF-I were infused: 6.7 nmol/kg.h, which induced hypoglycemia, and 2.0 nmol/kg.h, which did not. The effects were compared with an insulin infusion (0.17 nmol/kg.h) that had the same hypoglycemic potential as the high dose rhIGF-I infusion. rhIGF-II was infused at a rate of 6.7 nmol/kg.h. Primed constant infusions of isotopically labeled glucose, urea and leucine tracers were used to determine glucose and protein kinetics. rhIGF-I lowered blood glucose by increasing the rate of glucose clearance (P less than 0.01), in contrast to insulin, which both increased clearance and reduced glucose production. Net protein loss was reduced after infusion of low and high dose rhIGF-I and insulin by 11% (P less than 0.05), 15% (P less than 0.01), and 12% (P less than 0.05), respectively. rhIGF-II infusion did not alter the rate of net protein loss. In contrast to insulin, high dose rhIGF-I infusion increased the rate of protein synthesis in skeletal (P less than 0.05) and cardiac muscle (P less than 0.01) and in hepatic tissue (P less than 0.05). We conclude that (a) protein metabolism is more sensitive than glucose metabolism to rhIGF-I infusion, as protein loss was reduced by an rhIGF-I infusion that did not alter glucose kinetics; (b) protein synthesis is increased by rhIGF-I infusion but not by insulin infusion; and (c) rhIGF-II is a less effective anabolic agent than rhIGF-I. We speculate that the effects of rhIGF-I on protein metabolism are not mediated by insulin receptors.

Authors+Show Affiliations

Department of Surgery, University of Auckland, New Zealand.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

1864971

Citation

Douglas, R G., et al. "The Effects of Infusion of Insulinlike Growth Factor (IGF) I, IGF-II, and Insulin On Glucose and Protein Metabolism in Fasted Lambs." The Journal of Clinical Investigation, vol. 88, no. 2, 1991, pp. 614-22.
Douglas RG, Gluckman PD, Ball K, et al. The effects of infusion of insulinlike growth factor (IGF) I, IGF-II, and insulin on glucose and protein metabolism in fasted lambs. J Clin Invest. 1991;88(2):614-22.
Douglas, R. G., Gluckman, P. D., Ball, K., Breier, B., & Shaw, J. H. (1991). The effects of infusion of insulinlike growth factor (IGF) I, IGF-II, and insulin on glucose and protein metabolism in fasted lambs. The Journal of Clinical Investigation, 88(2), 614-22.
Douglas RG, et al. The Effects of Infusion of Insulinlike Growth Factor (IGF) I, IGF-II, and Insulin On Glucose and Protein Metabolism in Fasted Lambs. J Clin Invest. 1991;88(2):614-22. PubMed PMID: 1864971.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effects of infusion of insulinlike growth factor (IGF) I, IGF-II, and insulin on glucose and protein metabolism in fasted lambs. AU - Douglas,R G, AU - Gluckman,P D, AU - Ball,K, AU - Breier,B, AU - Shaw,J H, PY - 1991/8/1/pubmed PY - 1991/8/1/medline PY - 1991/8/1/entrez SP - 614 EP - 22 JF - The Journal of clinical investigation JO - J Clin Invest VL - 88 IS - 2 N2 - In vivo effects of 300-min infusions of recombinant insulinlike growth factor I (IGF-I) and IGF-II on glucose and protein metabolism have been investigated in awake, fasted lambs. Two doses of recombinant human (rh) IGF-I were infused: 6.7 nmol/kg.h, which induced hypoglycemia, and 2.0 nmol/kg.h, which did not. The effects were compared with an insulin infusion (0.17 nmol/kg.h) that had the same hypoglycemic potential as the high dose rhIGF-I infusion. rhIGF-II was infused at a rate of 6.7 nmol/kg.h. Primed constant infusions of isotopically labeled glucose, urea and leucine tracers were used to determine glucose and protein kinetics. rhIGF-I lowered blood glucose by increasing the rate of glucose clearance (P less than 0.01), in contrast to insulin, which both increased clearance and reduced glucose production. Net protein loss was reduced after infusion of low and high dose rhIGF-I and insulin by 11% (P less than 0.05), 15% (P less than 0.01), and 12% (P less than 0.05), respectively. rhIGF-II infusion did not alter the rate of net protein loss. In contrast to insulin, high dose rhIGF-I infusion increased the rate of protein synthesis in skeletal (P less than 0.05) and cardiac muscle (P less than 0.01) and in hepatic tissue (P less than 0.05). We conclude that (a) protein metabolism is more sensitive than glucose metabolism to rhIGF-I infusion, as protein loss was reduced by an rhIGF-I infusion that did not alter glucose kinetics; (b) protein synthesis is increased by rhIGF-I infusion but not by insulin infusion; and (c) rhIGF-II is a less effective anabolic agent than rhIGF-I. We speculate that the effects of rhIGF-I on protein metabolism are not mediated by insulin receptors. SN - 0021-9738 UR - https://www.unboundmedicine.com/medline/citation/1864971/The_effects_of_infusion_of_insulinlike_growth_factor__IGF__I_IGF_II_and_insulin_on_glucose_and_protein_metabolism_in_fasted_lambs_ L2 - https://doi.org/10.1172/JCI115346 DB - PRIME DP - Unbound Medicine ER -