Effect of carnitine loading on long-chain fatty acid oxidation, maximal exercise capacity, and nitrogen balance.
Carnitine has a potential effect on exercise capacity due to its role in the transport of long-chain fatty acids into the mitochondria for beta-oxidation, the export of acyl-coenzyme A compounds from mitochondria and the activation of branched-chain amino acid oxidation in the muscle. We studied the effect of carnitine supplementation on palmitate oxidation, maximal exercise capacity and nitrogen balance in rats. Daily carnitine supplementation (500 mg.kg-1 body mass for 6 weeks) was given to 30 rats, 15 of which were on an otherwise carnitine-free diet (group I) and 15 pair-fed with a conventional pellet diet (group II). A control group (group III, n = 6) was fed ad libitum the pellet diet. Palmitate oxidation was measured by collecting 14CO2 after an intraperitoneal injection of [1-14C]palmitate and exercise capacity by swimming to exhaustion. After carnitine supplementation carnitine concentrations in serum were supranormal [group I, total 150.8 (SD 48.5), free 78.9 (SD 18.4); group II, total 170.9 (SD 27.9), free 115.8 (SD 24.6) mumol.l-1] and liver carnitine concentrations were normal in both groups [group I, total 1.6 (SD 0.3), free 1.2 (SD 0.2); group II, total 1.3 (SD 0.3), free 0.9 (SD 0.2) mumol.g-1 dry mass]. In muscle carnitine concentrations were normal in group I [total 3.8 (SD 1.2), free 3.2 (SD 1.0) mumol.g-1 dry mass] and increased in group II [total 6.6 (SD 0.5), free 4.9 (SD 0.9) mumol.g-1 dry mass].(ABSTRACT TRUNCATED AT 250 WORDS)
Heinonen
O J
OJ
Paavo Nurmi Center, University of Turku, Finland.
Takala
J
J
Kvist
M H
MH
D000704:Analysis of Variance; D000818:Animals; D002331:Carnitine / Q000493:pharmacokinetics / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D010807:Physical Endurance / Q000187:drug effects; D005082:Physical Exertion / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D011919:Rats, Inbred Strains
D010169:Palmitic Acids; D019308:Palmitic Acid; D009584:Nitrogen; D002331:Carnitine