Go to JCI Insight
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Publication alerts by email
  • Advertising
  • Job board
  • Contact
  • Clinical Research and Public Health
  • Current issue
  • Past issues
  • By specialty
    • COVID-19
    • Cardiology
    • Gastroenterology
    • Immunology
    • Metabolism
    • Nephrology
    • Neuroscience
    • Oncology
    • Pulmonology
    • Vascular biology
    • All ...
  • Videos
    • Conversations with Giants in Medicine
    • Video Abstracts
  • Reviews
    • View all reviews ...
    • Complement Biology and Therapeutics (May 2025)
    • Evolving insights into MASLD and MASH pathogenesis and treatment (Apr 2025)
    • Microbiome in Health and Disease (Feb 2025)
    • Substance Use Disorders (Oct 2024)
    • Clonal Hematopoiesis (Oct 2024)
    • Sex Differences in Medicine (Sep 2024)
    • Vascular Malformations (Apr 2024)
    • View all review series ...
  • Viewpoint
  • Collections
    • In-Press Preview
    • Clinical Research and Public Health
    • Research Letters
    • Letters to the Editor
    • Editorials
    • Commentaries
    • Editor's notes
    • Reviews
    • Viewpoints
    • 100th anniversary
    • Top read articles

  • Current issue
  • Past issues
  • Specialties
  • Reviews
  • Review series
  • Conversations with Giants in Medicine
  • Video Abstracts
  • In-Press Preview
  • Clinical Research and Public Health
  • Research Letters
  • Letters to the Editor
  • Editorials
  • Commentaries
  • Editor's notes
  • Reviews
  • Viewpoints
  • 100th anniversary
  • Top read articles
  • About
  • Editors
  • Consulting Editors
  • For authors
  • Publication ethics
  • Publication alerts by email
  • Advertising
  • Job board
  • Contact
Top
  • View PDF
  • Download citation information
  • Send a comment
  • Terms of use
  • Standard abbreviations
  • Need help? Email the journal
  • Top
  • Abstract
  • Version history
  • Article usage
  • Citations to this article

Advertisement

Research Article Free access | 10.1172/JCI118217

Insulin and insulin-like growth factor-I enhance human skeletal muscle protein anabolism during hyperaminoacidemia by different mechanisms.

D A Fryburg, L A Jahn, S A Hill, D M Oliveras, and E J Barrett

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Find articles by Fryburg, D. in: PubMed | Google Scholar

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Find articles by Jahn, L. in: PubMed | Google Scholar

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Find articles by Hill, S. in: PubMed | Google Scholar

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Find articles by Oliveras, D. in: PubMed | Google Scholar

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Find articles by Barrett, E. in: PubMed | Google Scholar

Published October 1, 1995 - More info

Published in Volume 96, Issue 4 on October 1, 1995
J Clin Invest. 1995;96(4):1722–1729. https://doi.org/10.1172/JCI118217.
© 1995 The American Society for Clinical Investigation
Published October 1, 1995 - Version history
View PDF
Abstract

Insulin inhibits proteolysis in human muscle thereby increasing protein anabolism. In contrast, IGF-I promotes muscle protein anabolism principally by stimulating protein synthesis. As increases or decreases of plasma amino acids may affect protein turnover in muscle and also alter the muscle's response to insulin and/or IGF-I, this study was designed to examine the effects of insulin and IGF-I on human muscle protein turnover during hyperaminoacidemia. We measured phenylalanine balance and [3H]-phenylalanine kinetics in both forearms of 22 postabsorptive adults during a continuous [3H] phenylalanine infusion. Measurements were made basally and at 3 and 6 h after beginning a systemic infusion of a balanced amino acid mixture that raised arterial phenylalanine concentration about twofold. Throughout the 6 h, 10 subjects received insulin locally (0.035 mU/min per kg) into one brachial artery while 12 other subjects were given intraaterial IGF-I (100 ng/min per kg) to raise insulin or IGF-I concentrations, respectively, in the infused arm. The contralateral arm in each study served as a simultaneous control for the effects of amino acids (aa) alone. Glucose uptake and lactate release increased in the insulin- and IGF-I-infused forearms (P < 0.01) but did not change in the contralateral (aa alone) forearm in either study. In the aa alone arm in both studies, hyperaminoacidemia reversed the postabsorptive net phenylalanine release by muscle to a net uptake (P < 0.025, for each) due to a stimulation of muscle protein synthesis. In the hormone-infused arms, the addition of either insulin or IGF-I promoted greater positive shifts in phenylalanine balance than the aa alone arm (P < 0.01). With insulin, the enhanced anabolism was due to inhibition of protein degradation (P < 0.02), whereas IGF-I augmented anabolism by a further stimulation of protein synthesis above aa alone (P < 0.02). We conclude that: (a) hyperaminoacidemia specifically stimulates muscle protein synthesis; (b) insulin, even with hyperaminoacidemia, improves muscle protein balance solely by inhibiting proteolysis; and (c) hyperaminoacidemia combined with IGF-I enhances protein synthesis more than either alone.

Browse pages

Click on an image below to see the page. View PDF of the complete article

icon of scanned page 1722
page 1722
icon of scanned page 1723
page 1723
icon of scanned page 1724
page 1724
icon of scanned page 1725
page 1725
icon of scanned page 1726
page 1726
icon of scanned page 1727
page 1727
icon of scanned page 1728
page 1728
icon of scanned page 1729
page 1729
Version history
  • Version 1 (October 1, 1995): No description

Article tools

  • View PDF
  • Download citation information
  • Send a comment
  • Terms of use
  • Standard abbreviations
  • Need help? Email the journal

Metrics

  • Article usage
  • Citations to this article

Go to

  • Top
  • Abstract
  • Version history
Advertisement
Advertisement

Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)

Sign up for email alerts