Association between muscle acetyl-CoA and acetylcarnitine levels in the exercising horse.
Abstract: Treadmill exercise of 2-min duration and increasing intensity resulted in increased formation of acetyl-CoA and acetylcarnitine in working muscle of Thoroughbred horses. At high work intensities a plateau was reached for both acetyl-CoA (approximately 50 mumols/kg dry muscle) and acetylcarnitine (approximately 20 mmol/kg dry muscle). Postexercise concentrations were significantly (P less than 0.001) correlated; [acetylcarnitine] = 349.[acetyl-CoA] + 2.4. The results indicate that approximately 350 mumols acetylcarnitine were accumulated for every 1 mumol acetyl-CoA. Under the conditions of exercise used it is probable that most of the acetyl-CoA formed is generated through the intramitochondrial decarboxylation of pyruvate. The acetyl groups of acetyl-CoA are apparently redistributed throughout the whole cell through formation of acetylcarnitine, which readily transverses the mitochondrial membrane. Despite the redistribution, however, the close correlation between acetylcarnitine and acetyl-CoA would indicate that equilibrium was maintained and that neither acetylcarnitine transferase nor carnitine/acetylcarnitine translocase were rate limiting. There is some question as to whether the changes observed relate directly to exercise itself or to the state in muscle 10 s or more after exercise.
Publication Date: 1990-07-01 PubMed ID: 2394661DOI: 10.1152/jappl.1990.69.1.42Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the relationship between the levels of acetyl-CoA and acetylcarnitine in the muscle of racing horses during and after treadmill exercise. The researchers found that, with increased workout intensity, both acetyl-CoA and acetylcarnitine levels rose, suggesting acetyl-CoA conversion to acetylcarnitine for redistribution within cells.
Increased Acetyl-CoA and Acetylcarnitine During Exercise
- During treadmill exercise that lasted two minutes and had intensifying levels, the team of researchers noted increased amounts of acetyl-CoA and acetylcarnitine in the working muscles of Thoroughbred horses.
- When these horses were exercising at high-intensity levels, a plateau, or a state of little or no change after a time of activity or progress, was reached for both acetyl-CoA (approximately 50 mumols/kg dry muscle) and acetylcarnitine (around 20 mmol/kg dry muscle).
Post-exercise Correlation
- After exercise, concentrations of acetyl-CoA and acetylcarnitine were significantly correlated. The researchers noted that roughly 350 mumols of acetylcarnitine accumulated for every 1 mumol acetyl-CoA.
- In this study, the relationship between acetylcarnitine and acetyl-CoA indicates that equilibrium was maintained and that neither acetylcarnitine transferase nor carnitine/acetylcarnitine translocase were the limiting factor in this process.
Mechanism of Action: Acetyl-CoA Generation
- Under the exercise conditions used, it is likely that most of the acetyl-CoA formed is generated through the intramitochondrial decarboxylation of pyruvate. In other words, during exercise, pyruvate inside mitochondria is broken down to generate acetyl-CoA.
Redistribution via Acetylcarnitine
- The acetyl group of acetyl-CoA is considered to be redistributed throughout the entire cell through the creation of acetylcarnitine, which crosses the mitochondrial membrane easily.
- Even with this redistribution, the close correspondence between acetylcarnitine and acetyl-CoA levels means that balance is preserved within the cell.
Open Questions
- There remain questions about whether the changes observed in acetyl-CoA and acetylcarnitine directly relate to exercise or to the muscle state ten seconds or more after exercise.
Cite This Article
APA
Carlin JI, Harris RC, Cederblad G, Constantin-Teodosiu D, Snow DH, Hultman E.
(1990).
Association between muscle acetyl-CoA and acetylcarnitine levels in the exercising horse.
J Appl Physiol (1985), 69(1), 42-45.
https://doi.org/10.1152/jappl.1990.69.1.42 Publication
Researcher Affiliations
- Department of Clinical Chemistry I, Huddinge University Hospital, Karolinska Institutet, Sweden.
MeSH Terms
- Acetyl Coenzyme A / metabolism
- Acetylcarnitine / metabolism
- Animals
- Carnitine / analogs & derivatives
- Chloramphenicol O-Acetyltransferase / metabolism
- Coenzyme A / metabolism
- Horses
- Muscles / metabolism
- Physical Exertion / physiology
Citations
This article has been cited 9 times.- Meienberg F, Loher H, Bucher J, Jenni S, Krüsi M, Kreis R, Boesch C, Betz MJ, Christ E. The effect of exercise on intramyocellular acetylcarnitine (AcCtn) concentration in adult growth hormone deficiency (GHD). Sci Rep 2019 Dec 19;9(1):19431.
- Ren J, Lakoski S, Haller RG, Sherry AD, Malloy CR. Dynamic monitoring of carnitine and acetylcarnitine in the trimethylamine signal after exercise in human skeletal muscle by 7T 1H-MRS. Magn Reson Med 2013 Jan;69(1):7-17.
- Asterholm IW, Mundy DI, Weng J, Anderson RG, Scherer PE. Altered mitochondrial function and metabolic inflexibility associated with loss of caveolin-1. Cell Metab 2012 Feb 8;15(2):171-85.
- 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.
- van Loon LJ, Greenhaff PL, Constantin-Teodosiu D, Saris WH, Wagenmakers AJ. The effects of increasing exercise intensity on muscle fuel utilisation in humans. J Physiol 2001 Oct 1;536(Pt 1):295-304.
- al-Shurbaji A, Berglund L, Berge RK, Cederblad G, Humble E. On the interrelationship between hepatic carnitine, fatty acid oxidation, and triglyceride biosynthesis in nephrosis. Lipids 1997 Aug;32(8):847-52.
- Heinonen OJ. Carnitine and physical exercise. Sports Med 1996 Aug;22(2):109-32.
- Friolet R, Hoppeler H, Krähenbühl S. Relationship between the coenzyme A and the carnitine pools in human skeletal muscle at rest and after exhaustive exercise under normoxic and acutely hypoxic conditions. J Clin Invest 1994 Oct;94(4):1490-5.
- Caballero-García A, Noriega-González DC, Roche E, Drobnic F, Córdova A. Effects of L-Carnitine Intake on Exercise-Induced Muscle Damage and Oxidative Stress: A Narrative Scoping Review. Nutrients 2023 May 31;15(11).
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