Effect of dietary fats with odd or even numbers of carbon atoms on metabolic response and muscle damage with exercise in Quarter Horse-type horses with type 1 polysaccharide storage myopathy.
OBJECTIVE
To evaluate effects of fats with odd and even numbers of carbon atoms on muscle metabolism in exercising horses with polysaccharide storage myopathy (PSSM).


METHODS
8 horses with PSSM (6 females and 2 males; mean +/- SD age, 6.3 +/- 3.9 years).


METHODS
Isocaloric diets (grain, triheptanoin, corn oil, and high-fat, low-starch [HFLS] feed) were fed for 3 weeks each; horses performed daily treadmill exercise. Grain was fed to establish an exercise target, and HFLS feed was fed as a negative control diet. Daily plasma samples were obtained. For each diet, a 15-minute exercise test was performed, and gluteus medius muscle specimens and blood samples were obtained before and after exercise.


RESULTS
Feeding triheptanoin, compared with the corn oil diet, resulted in exercise intolerance; higher plasma creatine kinase (CK) activity and concentrations of C3:0- and C7:0-acylcarnitine and insulin; and lower concentrations of nonesterified fatty acids (NEFA) and C16:0-, C18:1-, and C18:2-acylcarnitine, without changes in concentrations of plasma glucose or resting muscle substrates and metabolites. Feeding grain induced higher CK activity and insulin concentrations and lower NEFA concentrations than did corn oil or HFLS feed. Feeding grain induced higher glucose concentrations than did triheptanoin and corn oil. In muscle, feeding grain resulted in lower glucose-6-phosphate, higher citrate, and higher postexercise lactate concentrations than did the other diets.


CONCLUSIONS
Triheptanoin had detrimental effects, reflecting decreased availability of NEFA, increased insulin stimulation of glycogen synthesis, and potential inhibition of lipid oxidation. Long-chain fats are the best dietetic for PSSM.
Borgia
Lisa A
LA
Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA. borgi003@umn.edu
Valberg
Stephanie J
SJ
McCue
Molly E
ME
Pagan
Joe D
JD
Roe
Charles R
CR
D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003402:Creatine Kinase / Q000097:blood; D004041:Dietary Fats / Q000494:pharmacology*; D002523:Edible Grain; D005260:Female; D006734:Horse Diseases / Q000097:blood / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D006736:Horses / Q000145:classification / Q000502:physiology*; D007328:Insulin / Q000097:blood; D008297:Male; D008660:Metabolism / Q000187:drug effects; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D009135:Muscular Diseases / Q000097:blood / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D010805:Physical Conditioning, Animal / Q000009:adverse effects*; D012420:Running; D013045:Species Specificity; D016138:Walking
D001786:Blood Glucose; D004041:Dietary Fats; D007328:Insulin; D003402:Creatine Kinase