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 has an altmetric score of 3

See more details

Referenced in 1 Wikipedia pages
17 readers on Mendeley
  • Article usage
  • Citations to this article (117)

Advertisement

Research Article Free access | 10.1172/JCI108275

The essentiality of insulin and the role of glucagon in regulating glucose utilization and production during strenuous exercise in dogs.

M Vranic, R Kawamori, S Pek, N Kovacevic, and G A Wrenshall

Find articles by Vranic, M. in: JCI | PubMed | Google Scholar

Find articles by Kawamori, R. in: JCI | PubMed | Google Scholar

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

Find articles by Kovacevic, N. in: JCI | PubMed | Google Scholar

Find articles by Wrenshall, G. in: JCI | PubMed | Google Scholar

Published February 1, 1976 - More info

Published in Volume 57, Issue 2 on February 1, 1976
J Clin Invest. 1976;57(2):245–255. https://doi.org/10.1172/JCI108275.
© 1976 The American Society for Clinical Investigation
Published February 1, 1976 - Version history
View PDF
Abstract

In order to elucidate the role of insulin and glucagon during strenuous exercise (100 m/min, slope 10-12 degrees), we have determined the rates of production (Ra), utilization (Rd), and metabolic clearance (M) of glucose in normal dogs before pancreatectomy and 2 wk after total pancreatectomy (a) when they were being maintained on constant intraportal basal insulin infusion, (245 muU/kg-min) and (b) when insulin supply had been withheld before and during exercise. Such an intense exercise induced in normal dogs a prompt decrease in mean immunoreactive serum insulin (IRI) from 20 +/- 3 to 11 +/- 2 muU/ml. In depancreatized insulin-infused dogs serum IRI during rest and exercise was between 14 +/- 1 and 12 +/- 2 muU/ml. In the third group, after cessation of insulin infusion, IRI decreased by 76% (from 17 +/- 5 to 4 +/- 1) and did not decrease futher during exercise. During exercise, serum immunoreactive glucagon (IRG) increased threefold in normal dogs. In depancreatized dogs serum IRG was the same as in normal resting dogs (indicating a nonpancreatic source of the hormone) but it did not increase during exercise. In normal dogs exercise induced proportional increases in Ra, Rd, and M (threefold) and normoglycemia was maintained. Changes in glucose turnover in depancreatized insulin-infused dogs were similar to those seen in normal dogs suggesting that a decrease in insulin secretion and a rise in IRG are not essential to prevent hypoglycemia in diabetic dogs. With the cessation of insulin infusion in resting depancreatized dogs, Ra increased, M decreased, and hyperglycemia ensued. During exercise, Ra continued to rise, but M did not increase significantly. Conclusions: (a) Regulation of glucose production by liver during exercise is multifactorial. A decrease in IRI and an increase in IRG are not the only factors which can promote delivery of glucose to the peripheral tissues. The insulin glucagon molar ratio was found not to be an essential metabolic functional unit in regulating glucose metabolism during exercise. (b) It is hypothesized that increases in blood flow and capillary surface area can lead to an increase in the amount of insulin delivered to the muscle even when serum levels of IRI are reduced during exercies. It is suggested that small, but adequate amounts of insulin (as found in normal and depancreatized insulin-infused dogs) are essential in regulating glucose uptake in the working muscle. (c) Since totally depancreatized dogs had normal serum levels of IRG (originating presumably from the gastrointestinal tract), the question of essentiality of basal glucagon activity in glucose homeostasis during exercise could not be resolved by these experiments. It appears, however, that regulation of secretion of nonpancreatic glucagon differs from that of pancreatic glucagon.

Images.

Browse pages

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

icon of scanned page 245
page 245
icon of scanned page 246
page 246
icon of scanned page 247
page 247
icon of scanned page 248
page 248
icon of scanned page 249
page 249
icon of scanned page 250
page 250
icon of scanned page 251
page 251
icon of scanned page 252
page 252
icon of scanned page 253
page 253
icon of scanned page 254
page 254
icon of scanned page 255
page 255
Version history
  • Version 1 (February 1, 1976): No description

Article tools

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

Metrics

Article has an altmetric score of 3
  • Article usage
  • Citations to this article (117)

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

Referenced in 1 Wikipedia pages
17 readers on Mendeley
See more details