title: L-arginine reduces exercise-induced increase in plasma lactate and ammonia.
abstract: To investigate the effect of L-arginine supplementation (L-ARG) on physiological and metabolic changes during exercise, we determined in a double-blind study the cardiorespiratory (heart rate, oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) and the metabolic (lactate and ammonia) responses to maximal exercise after either an intravenous L-ARG hydrochloride salt or placebo load in 8 healthy subjects. Exercise-induced increases in heart rate, VO(2) and VCO(2) were not significantly different after L-ARG or placebo. By contrast, peak plasma ammonia and lactate were significantly decreased after L-ARG load (60.6 +/- 8.2 vs. 73.1 +/- 9.1 micro mol x l(-1), p < 0.01 and 7.1 +/- 0.7 vs. 8.2 +/- 1.1 mmol x l(-1), p < 0.01, for ammonia and lactate, respectively). Plasma L-citrulline increased significantly during exercise only after L-ARG load, despite a concomitant decrease in plasma L-ARG. Furthermore, a significant inverse relationship was observed between changes in lactate and L-citrulline concentrations after L-ARG load (r = -0.84, p = 0.009). These results demonstrate that intravenous L-ARG reduces significantly exercise-induced increase in plasma lactate and ammonia. Taken together, the specific L-citrulline increase and the inverse relationship observed between L-citrulline and plasma lactate after L-ARG might support that L-ARG supplementation enhances the L-arginine-nitric oxide (NO) pathway during exercise.
authors.affiliation: Service des Explorations Fonctionnelles Respiratoires et de l'Exercice et EA 3072, Hôpitaux Universitaires et Faculté de Médecine, Strasbourg, France. Adrien.Schaefer@physio-ulp.u-strasbg.fr
authors.forename: A
authors.initials: A
authors.lastname: Schaefer
authors.forename: F
authors.initials: F
authors.lastname: Piquard
authors.forename: B
authors.initials: B
authors.lastname: Geny
authors.forename: S
authors.initials: S
authors.lastname: Doutreleau
authors.forename: E
authors.initials: E
authors.lastname: Lampert
authors.forename: B
authors.initials: B
authors.lastname: Mettauer
authors.forename: J
authors.initials: J
authors.lastname: Lonsdorfer
mesh_terms: D000328:Adult; D000641:Ammonia / Q000097:blood*; D001120:Arginine / Q000097:blood / Q000494:pharmacology*; D002956:Citrulline / Q000097:blood; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007773:Lactates / Q000097:blood*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009952:Ornithine / Q000097:blood
chemical_list: D007773:Lactates; D002956:Citrulline; D009569:Nitric Oxide; D000641:Ammonia; D001120:Arginine; D009952:Ornithine