title: L-Arginine infusion increases glucose clearance during prolonged exercise in humans.
abstract: Nitric oxide synthase (NOS) inhibition has been shown in humans to attenuate exercise-induced increases in muscle glucose uptake. We examined the effect of infusing the NO precursor L-arginine (L-Arg) on glucose kinetics during exercise in humans. Nine endurance-trained males cycled for 120 min at 72+/-1% Vo(2 peak) followed immediately by a 15-min "all-out" cycling performance bout. A [6,6-(2)H]glucose tracer was infused throughout exercise, and either saline alone (Control, CON) or saline containing L-Arg HCL (L-Arg, 30 g at 0.5 g/min) was confused in a double-blind, randomized order during the last 60 min of exercise. L-Arg augmented the increases in glucose rate of appearance, glucose rate of disappearance, and glucose clearance rate (L-Arg: 16.1+/-1.8 ml.min(-1).kg(-1); CON: 11.9+/- 0.7 ml.min(-1).kg(-1) at 120 min, P<0.05) during exercise, with a net effect of reducing plasma glucose concentration during exercise. L-Arg infusion had no significant effect on plasma insulin concentration but attenuated the increase in nonesterified fatty acid and glycerol concentrations during exercise. L-Arg infusion had no effect on cycling exercise performance. In conclusion, L-Arg infusion during exercise significantly increases skeletal muscle glucose clearance in humans. Because plasma insulin concentration was unaffected by L-Arg infusion, greater NO production may have been responsible for this effect.
authors.affiliation: Deptartment of Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia. mcconell@unimelb.edu.au
authors.forename: G K
authors.initials: GK
authors.lastname: McConell
authors.forename: N N
authors.initials: NN
authors.lastname: Huynh
authors.forename: R S
authors.initials: RS
authors.lastname: Lee-Young
authors.forename: B J
authors.initials: BJ
authors.lastname: Canny
authors.forename: G D
authors.initials: GD
authors.lastname: Wadley
mesh_terms: D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D001786:Blood Glucose / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005990:Glycerol / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D008297:Male; D008657:Metabolic Clearance Rate; D009569:Nitric Oxide / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D002245:Carbon Dioxide; D009569:Nitric Oxide; D001120:Arginine; D005947:Glucose; D005990:Glycerol