Metabolic responses to exercise in the racehorse: changes in plasma alanine concentration.
Abstract: Previous studies in humans have shown that alanine is released from the skeletal muscle in proportion to the work load. We have measured plasma alanine and urea concentrations in well-trained Standardbred and Finnish-bred (cold-blooded) trotters after a graded-intensity exercise and during recovery to study metabolic responses to exercise in this animal model. As controls we measured blood lactate, pyruvate, and glucose concentrations as well as hematocrit values. Metabolic responses to exercise were closely reflected in all these parameters. Plasma alanine increased relatively more than plasma lactate at moderate-intensity exercise near anaerobic threshold. The linear correlation between the intensity of exercise and plasma alanine was similar to that observed earlier in humans. Interestingly, plasma alanine concentrations remained elevated long after the submaximal exercise, whereas the concentration of lactate, pyruvate, and glucose decreased more rapidly. No significant changes were found in plasma urea concentration under these conditions. The most significant differences in the metabolic responses to exercise of the two breeds studied were the higher lactate-to-pyruvate ratios achieved during the high-intensity exercise and the more sensitive increases of plasma alanine even during low-intensity exercise in the Finnish-bred horses. These differences probably reflect different compositions of muscle fiber types in the two breeds. The findings together indicate that plasma alanine is greatly increased in the racehorse during and after a high-intensity exercise and thus is an important vehicle in transporting ammonia and carbon skeletons of products of anaerobic glycolysis out of the muscle tissue.
Publication Date: 1987-12-01 PubMed ID: 3436858DOI: 10.1152/jappl.1987.63.6.2195Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the metabolic reactions to physical activity in racehorses, focusing on alterations in plasma alanine levels. Using well-conditioned Standardbred and Finnish-bred trotters, the study reveals that plasma alanine increases significantly during and after strenuous exercise, functioning as a key transporter of ammonia and byproducts of anaerobic glycolysis out of the muscle tissue.
Research Methodology
- The study measured plasma alanine and urea concentrations in well-trained grade trotters of two breeds (Standardbred and Finnish-bred) following varied intensity exercise and during the recovery period.
- Blood lactate, pyruvate, glucose concentrations and hematocrit values were measured as control parameters.
Key Findings
- The researchers discovered that metabolic responses to exercises are closely mirrored in these parameters. Plasma alanine increased relatively more than plasma lactate at moderate-intensity exercise, approximating the anaerobic threshold.
- The connection between the intensity of exercise and plasma alanine mirrored that which had been previously observed in human studies.
- Post-exercise, plasma alanine levels stayed raised for an extended period, while lactate, pyruvate, and glucose concentrations tended to decrease more rapidly.
- No significant alterations were observed in plasma urea concentration under the conditions of this study.
Comparison of Breeds
- The study uncovered breed-specific differences in metabolic responses to exercise. The most noteworthy disparities were the higher lactate-to-pyruvate ratios achieved during high-intensity exercise and the more sensitive increases of plasma alanine even during low-intensity exercise in the Finnish-bred horses.
- These breed-related differences are possibly indicative of various compositions of muscle fiber types in the two breeds.
Conclusion
- The study indicates that plasma alanine significantly increases in racehorses during and following high-intensity exercise.
- This indicates its crucial role in transporting ammonia and the carbon residue of anaerobic glycolysis products out of the muscle tissue.
Cite This Article
APA
Pösö AR, Soveri T, Alaviuhkola M, Lindqvist L, Alakuijala L, Mäenpää PH, Oksanen HE.
(1987).
Metabolic responses to exercise in the racehorse: changes in plasma alanine concentration.
J Appl Physiol (1985), 63(6), 2195-2200.
https://doi.org/10.1152/jappl.1987.63.6.2195 Publication
Researcher Affiliations
- Department of Biochemistry, College of Veterinary Medicine, Helsinki, Finland.
MeSH Terms
- Alanine / blood
- Animals
- Blood Glucose / analysis
- Female
- Hematocrit
- Horses / metabolism
- Lactates / blood
- Male
- Physical Exertion
- Pyruvates / blood
- Urea / blood
Citations
This article has been cited 1 times.- Alberghina D, Piccione G, Amorini AM, D'Urso S, Longo S, Picardi M, Tavazzi B, Lazzarino G. Modulation of circulating purines and pyrimidines by physical exercise in the horse.. Eur J Appl Physiol 2011 Mar;111(3):549-56.
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