title: Effect of carnitine, acetyl-, and propionylcarnitine supplementation on the body carnitine pool, skeletal muscle composition, and physical performance in mice.
abstract: OBJECTIVE
  Pharmacokinetics and effects on skeletal muscle and physical performance of oral acetylcarnitine and propionylcarnitine are not well characterized. We therefore investigated the influence of oral acetylcarnitine, propionylcarnitine, and carnitine on body carnitine homeostasis, energy metabolism, and physical performance in mice and compared the findings to non-supplemented control animals.
  
  
  METHODS
  Mice were supplemented orally with 2 mmol/kg/day carnitine, acetylcarnitine, or propionylcarnitine for 4 weeks and studied either at rest or after exhaustive exercise.
  
  
  RESULTS
  In the supplemented groups, total plasma and urine carnitine concentrations were significantly higher than in the control group receiving no carnitine, whereas the skeletal muscle carnitine content remained unchanged. The supplemented acylcarnitines were hydrolyzed in intestine and liver and reached the systemic circulation as carnitine. Bioavailability of carnitine and acylcarnitines, determined as the urinary excretion of total carnitine, was in the range of 19 %. Skeletal muscle morphology, including fiber-type composition, was not affected, and oxygen consumption by soleus or gastrocnemius fibers was not different between the groups. Supplementation with carnitine or acylcarnitines had no significant impact on the running capacity, but was associated with lower plasma lactate levels and a higher glycogen content in white skeletal muscle after exhaustive exercise.
  
  
  CONCLUSIONS
  Oral supplementation of carnitine, acetylcarnitine, or propionylcarnitine in mice is associated with increased plasma and urine total carnitine concentrations, but does not affect the skeletal muscle carnitine content. Despite better preservation of skeletal muscle glycogen and lower plasma lactate levels, physical performance was not improved by carnitine or acylcarnitine supplementation.
authors: Clinical Pharmacology and Toxicology, University Hospital Basel, 4031, Basel, Switzerland.
authors: Réjane
authors: R
authors: Morand
authors: Jamal
authors: J
authors: Bouitbir
authors: Andrea
authors: A
authors: Felser
authors: Jürgen
authors: J
authors: Hench
authors: Christoph
authors: C
authors: Handschin
authors: Stephan
authors: S
authors: Frank
authors: Stephan
authors: S
authors: Krähenbühl
mesh_terms: D000108:Acetylcarnitine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002331:Carnitine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D019587:Dietary Supplements; D004734:Energy Metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal
chemical_list: D015415:Biomarkers; C116917:acylcarnitine; C003223:propionylcarnitine; D000108:Acetylcarnitine; D002331:Carnitine