Metabolic changes induced by maximal exercise in human subjects following L-carnitine administration.
In double-blind cross-over experiments, ten moderately trained male subjects were submitted to two bouts of maximal cycle ergometer exercise separated by a 3 day interval. Each subject was randomly given either L-carnitine (2 g) or placebo orally 1 h before the beginning of each exercise session. At rest L-carnitine supplementation resulted in an increase of plasma-free carnitine without a change in acid-soluble carnitine esters. Treatment with L-carnitine induced a significant post-exercise decrease of plasma lactate and pyruvate and a concurrent increase of acetylcarnitine. The determination of the individual carnitine esters in urine collected for 24 h after the placebo exercise trial revealed a decrease of acetyl carnitine and a parallel increase of a C4 carnitine ester, probably isobutyrylcarnitine. Conversely, acetylcarnitine was strongly increased and C4 compounds were almost suppressed in the L-carnitine loading trial. These results suggest that L-carnitine administration prior to high-intensity exercise stimulates pyruvate dehydrogenase activity, thus diverting pyruvate from lactate to acetylcarnitine formation.
Siliprandi
N
N
Istituto di Fisiopatologia Medica, Università di Chieti, Italy.
Di Lisa
F
F
Pieralisi
G
G
Ripari
P
P
Maccari
F
F
Menabo
R
R
Giamberardino
M A
MA
Vecchiet
L
L
D000108:Acetylcarnitine / Q000378:metabolism; D000328:Adult; D002331:Carnitine / Q000378:metabolism / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise; D006801:Humans; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid
D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; D000108:Acetylcarnitine; D019289:Pyruvic Acid; D002331:Carnitine