Plasma acylcarnitine and fatty acid profiles during exercise and training in Standardbreds.
OBJECTIVE
To evaluate alterations in skeletal muscle carnitine metabolism during exercise and training by measuring changes in plasma acylcarnitine concentrations in Standardbreds.


METHODS
10 Standardbred geldings with a mean +/- SD age of 20 +/- 2 months and weight of 384 +/- 42 kg.


METHODS
In a 32-week longitudinal study, training on a treadmill was divided into 4 phases as follows: phase 1, acclimatization for 4 weeks; phase 2, 18 weeks with alternating endurance and high-intensity exercise training; phase 3, increased training volume and intensity for another 6 weeks; and phase 4, deconditioning for 4 weeks. In phase 3, horses were randomly assigned to 2 groups as follows: control horses (which continued training at the same level as in phase 2) and high-intensity exercise trained horses. At the end of each phase, a standardized exercise test (SET) was performed. Plasma acylcarnitine, fatty acids, and lactic acid and serum beta-hydroxybutyric acid (BHBA) concentrations were assessed before and at different time points after each SET.


RESULTS
Plasma lactic acid, total nonesterified fatty acids, 3-hydroxyisobutyric acid, and acetylcarnitine (C2-carnitine) concentrations significantly increased during SETs, whereas serum BHBA, plasma propionylcarnitine (C3-carnitine), and plasma butyryl- and isobutyrylcarnitine (C4-carnitine) concentrations decreased significantly, compared with those before SETs.


CONCLUSIONS
Our findings indicated that the plasma acylcarnitine profile in horses likely reflects skeletal muscle carnitine metabolism following exercise, thereby providing a possible practical method to investigate potential disorders in carnitine metabolism in horses with myopathy.
Westermann
Cornélie M
CM
Department of Equine Sciences, Medicine Section, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.
Dorland
Bert
B
de Sain-van der Velden
Monique G
MG
Wijnberg
Inge D
ID
Van Breda
Eric
E
De Graaf-Roelfsema
Ellen
E
Keizer
Hans A
HA
Van der Kolk
Johannes H
JH
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood; D005227:Fatty Acids / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry; D006736:Horses / Q000097:blood / Q000378:metabolism*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*
D005227:Fatty Acids; C116917:acylcarnitine; D019344:Lactic Acid; D002331:Carnitine; D020155:3-Hydroxybutyric Acid