Total carnitine content of the middle gluteal muscle of thoroughbred horses: normal values, variability and effect of acute exercise.
Abstract: There was no detectable loss of total carnitine associated with intense exercise from the middle gluteal muscle of Thoroughbred horses. Measurements made on a single biopsy obtained during the course of a normal training and exercise programme may, therefore, be considered representative of the normal content at rest. The variability in total carnitine content within the normal muscle biopsy area amounted to 13.2 per cent of the normal mean content. Approximately 50 per cent of this variability could be attributed to covariation with citrate synthase, to which it was highly significantly correlated. The muscle carnitine content of yearling Thoroughbred horses ranged from 10.5 to 18.8 mmol/kg dry muscle (dm); the ranges in untrained, lightly trained and fully trained two-year-olds were 18.5 to 34.7, 14.1 to 24.2 and 22.9 to 26.9 mmol/kg dm, respectively. In horses aged over three years total carnitine ranged from 21.3 to 35.5 mmol/kg dm. A trend toward higher contents of total carnitine with age and training appeared to be largely a consequence of underlying changes in mitochondria density as indicated by differences in levels of citrate synthase activity. There was a marked difference in ratios of total carnitine to citrate synthase activity between training yards, reflecting possible differences in management regimens and/or bloodstock selection.
Publication Date: 1992-01-01 PubMed ID: 1555541DOI: 10.1111/j.2042-3306.1992.tb02779.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research looked at the total carnitine content of Thoroughbred horse’s middle gluteal muscle and found no detectable loss after intense exercise. The research also highlighted variability in the total carnitine content, with about half this variability linked with citrate synthase.
Understanding Carnitine and Exercise in Horses
- The research primarily focused on carnitine, a substance crucial for energy processing in cells, particularly in skeletal muscles. The study aimed to analyze its relationship with intense exercise, using Thoroughbred horses as subjects.
- Intense exercise didn’t cause a detectable loss of carnitine in the middle gluteal muscle, a significant muscle used during horse locomotion. Therefore, measurements taken from single muscle biopsies during a routine training schedule could be considered representative of the normal carnitine content while resting.
Variability in Carnitine Content
- The research observed a variability in total carnitine content within the biopsy area, approximately 13.2% of the average, indicating that the carnitine level can fluctuate within a defined region.
- Interestingly, about half of this variability could be attributed to correlation with an enzyme called citrate synthase, which is crucial for energy production in cells. Citrate synthase activity strongly correlated with carnitine content, suggesting that variable enzyme activity could affect carnitine levels.
Carnitine Content across Different Ages and Training Levels
- The study observed that carnitine content varied between untrained, lightly trained, and fully trained two-year-old horses, and yearling (one-year-old) horses, with the ranges escalating alongside training level.
- In horses older than three years, the total carnitine content range was observed to be even higher. This suggests that an increase in carnitine content could be a function of age and training.
- However, this perceived increase in carnitine content with age and training may also relate to the changes in mitochondria density, as indicated by variations in citrate synthase levels. That’s because mitochondria, the cellular powerplants, use carnitine for energy production. Thus, larger mitochondrial density could imply greater carnitine content.
Differences between Training Yards
- The research also found a significant difference in the ratio of carnitine to citrate synthase activity between different training yards. This suggests that varying management methods and selection of horses (bloodstock) could influence these metabolic markers in a systemic manner.
Cite This Article
APA
Foster CV, Harris RC.
(1992).
Total carnitine content of the middle gluteal muscle of thoroughbred horses: normal values, variability and effect of acute exercise.
Equine Vet J, 24(1), 52-57.
https://doi.org/10.1111/j.2042-3306.1992.tb02779.x Publication
Researcher Affiliations
- Department of Comparative Physiology, Animal Health Trust, Newmarket, Suffolk, UK.
MeSH Terms
- Animals
- Buttocks
- Carnitine / analysis
- Carnitine / blood
- Citrate (si)-Synthase / analysis
- Female
- Horses / metabolism
- Horses / physiology
- Lactates / blood
- Male
- Muscles / chemistry
- Muscles / enzymology
- Muscles / metabolism
- Physical Exertion / physiology
- Reference Values
Citations
This article has been cited 2 times.- Stephens FB, Constantin-Teodosiu D, Greenhaff PL. New insights concerning the role of carnitine in the regulation of fuel metabolism in skeletal muscle. J Physiol 2007 Jun 1;581(Pt 2):431-44.
- Heinonen OJ. Carnitine and physical exercise. Sports Med 1996 Aug;22(2):109-32.
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