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Home / Equine Research Bank / J Appl Physiol (1985) / beta-adrenergic blockade augments glucose utilization in hor...
Journal of applied physiology (Bethesda, Md. : 1985)2000; 89(3); 1086-1098; doi: 10.1152/jappl.2000.89.3.1086

beta-adrenergic blockade augments glucose utilization in horses during graded exercise.

Abstract: To examine the role of beta-adrenergic mechanisms in the regulation of endogenous glucose (Glu) production [rate of appearance (R(a))] and utilization [rate of disappearance (R(d))] and carbohydrate (CHO) metabolism, six horses completed consecutive 30-min bouts of exercise at approximately 30% (Lo) and approximately 60% (Hi) of estimated maximum O(2) uptake with (P) and without (C) prior administration of the beta-blocker propranolol (0.22 mg/kg iv). All horses completed exercise in C; exercise duration in P was 49.9 +/- 1.2 (SE) min. Plasma Glu was unchanged in C during Lo but increased progressively in Hi. In P, plasma Glu rose steadily during Lo and Hi and was higher (P < 0.05) than in C throughout exercise. Plasma insulin declined during exercise in P but not in C; beta-blockade attenuated (P < 0.05) the rise in plasma glucagon and free fatty acids and exaggerated the increases in epinephrine and norepinephrine. Glu R(a) was 8.1 +/- 0.8 and 8.4 +/- 1.0 micromol. kg(-1). min(-1) at rest and 30.5 +/- 3.6 and 42.8 +/- 4.1 micromol. kg(-1). min(-1) at the end of Lo in C and P, respectively. During Hi, Glu R(a) increased to 54.4 +/- 4.4 and 73.8 +/- 4.7 micromol. kg(-1). min(-1) in C and P, respectively. Similarly, Glu R(d) was approximately 40% higher in P than in C during Lo (27.3 +/- 2.0 and 39.5 +/- 3.3 micromol. kg(-1). min(-1) in C and P, respectively) and Hi (37.4 +/- 2.6 and 61.5 +/- 5.3 micromol. kg(-1). min(-1) in C and P, respectively). beta-Blockade augmented CHO oxidation (CHO(ox)) with a concomitant reduction in fat oxidation. Inasmuch as estimated muscle glycogen utilization was similar between trials, the increase in CHO(ox) in P was due to increased use of plasma Glu. We conclude that beta-blockade increases Glu R(a) and R(d) and CHO(ox) in horses during exercise. The increase in Glu R(d) under beta-blockade suggests that beta-adrenergic mechanisms restrain Glu R(d) during exercise.
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Publication Date: 2000-08-24 PubMed ID: 10956355DOI: 10.1152/jappl.2000.89.3.1086Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research examines the effects of beta-blockers on glucose metabolism in horses during exercise. The study found that administering the beta-blocker propranolol results in increased glucose production and usage, as well as increased carbohydrate oxidation.

Introduction

  • The study aimed to explore the role of beta-adrenergic mechanisms in regulating glucose production and utilization, as well as carbohydrate metabolism in horses.
  • The role of this mechanism was examined in the context of graded exercises, with six horses participating in the study. The horses were made to complete a 30-minute bout of exercise at varying intensity levels with and without the beta-blocker propranolol.

Methodology

  • The exercise sessions were conducted at about 30% and 60% of the estimated maximum oxygen uptake.
  • The horses were administered propranolol – a beta-blocker at a dose of 0.22 mg/kg intravenously.
  • Parameters such as plasma glucose levels, insulin levels, glucagon, free fatty acids and other hormonal markers were measured and monitored throughout the experiment.

Results

  • All horses were able to complete the exercises without any prior administration of beta-blockers. However, when the horses were given propranolol, plasma glucose levels increased consistently throughout both low and high intensity exercises.
  • Additionally, there was an observed decrease in plasma insulin during exercise in the propranolol group. Similarly, the administration of the beta-blocker was found to limit the increase in glucagon and free fatty acids and exacerbate the increases in epinephrine and norepinephrine.
  • Remarkably, glucose production and discharge rates were found to be higher in horses during the exercise that were given propranolol, compared to those without. This suggests that beta-blockade could augment carbohydrate oxidation accompanied by a reduction in fat-oxidation.
  • According to the study’s findings, increased carbohydrate oxidation in horses administered propranolol was due to the increased usage of plasma glucose.

Conclusion

  • The investigation therefore concludes that administering beta-blockers such as propranolol can enhance glucose production, utilisation rates and carbohydrate oxidation during exercise in horses.
  • The increased glucose discharge under a beta-blocker suggests that beta-adrenergic mechanisms may inhibit glucose discharge during exercise.

Cite This Article

APA
Geor RJ, Hinchcliff KW, Sams RA. (2000). beta-adrenergic blockade augments glucose utilization in horses during graded exercise. J Appl Physiol (1985), 89(3), 1086-1098. https://doi.org/10.1152/jappl.2000.89.3.1086

Publication

Journal of applied physiology (Bethesda, Md. : 1985)
ISSN: 8750-7587
NlmUniqueID: 8502536
Country: United States
Language: English
Volume: 89
Issue: 3
Pages: 1086-1098

Researcher Affiliations

Geor, R J
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA. rgeor@ker.com
Hinchcliff, K W
    Sams, R A

      MeSH Terms

      • Adrenergic beta-Antagonists / pharmacology
      • Animals
      • Blood Glucose / analysis
      • Blood Proteins / analysis
      • Carbohydrate Metabolism
      • Epinephrine / metabolism
      • Fatty Acids, Nonesterified / blood
      • Female
      • Glucose / metabolism
      • Glycerol / blood
      • Hematocrit
      • Hormones / blood
      • Horses / metabolism
      • Kinetics
      • Lactic Acid / blood
      • Male
      • Motor Activity / physiology
      • Norepinephrine / metabolism
      • Oxidation-Reduction
      • Propranolol / pharmacology
      • Pulmonary Gas Exchange

      Citations

      This article has been cited 3 times.
      1. Ferlazzo A, Cravana C, Fazio E, Medica P. The different hormonal system during exercise stress coping in horses. Vet World 2020 May;13(5):847-859.
        doi: 10.14202/vetworld.2020.847-859pubmed: 32636578google scholar: lookup
      2. Echigoya Y, Okabe H, Itou T, Endo H, Sakai T. Molecular characterization of glycogen synthase 1 and its tissue expression profile with type II hexokinase and muscle-type phosphofructokinase in horses. Mol Biol Rep 2011 Jan;38(1):461-9.
        doi: 10.1007/s11033-010-0129-8pubmed: 20383748google scholar: lookup
      3. Gu J, Orr N, Park SD, Katz LM, Sulimova G, MacHugh DE, Hill EW. A genome scan for positive selection in thoroughbred horses. PLoS One 2009 Jun 2;4(6):e5767.
        doi: 10.1371/journal.pone.0005767pubmed: 19503617google scholar: lookup
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