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Med Sci Sports Exerc. 2011 Sep;43(9):1626-34. doi: 10.1249/MSS.0b013e318212a317.

Effect of l-arginine infusion on glucose disposal during exercise in humans.

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1
Exercise Physiology and Metabolism Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia.

Abstract

PURPOSE:

We have previously shown that local infusion of a nitric oxide synthase (NOS) inhibitor attenuates increases in leg glucose uptake during exercise in humans. We have also shown that infusion of the NOS substrate, l-arginine (l-Arg), increases glucose clearance, although the mechanisms involved were not determined. A potential mechanism for NO-mediated glucose disposal is via interactions with NOS and the energy sensor AMP-activated protein kinase (AMPK). The aim of this study was to determine the mechanism(s) by which l-Arg infusion increases glucose disposal during exercise in humans by examining total NOS activity and AMPK signaling.

METHODS:

Seven males cycled for 120 min at 64% ± 1% VO(2)peak, during which the [6,6-H]glucose tracer was infused. During the final 60 min of exercise, either saline alone (Control, CON), or saline containing l-Arg HCl (l-Arg, 30 g at 0.5 g·min(-1)) was coinfused in a double-blind, randomized, counterbalanced order.

RESULTS:

l-Arg increased the glucose rate of disappearance and glucose clearance rate during exercise; however, this was accompanied by a 150% increase in plasma insulin concentration from 65 to 75 min (P < 0.05) that remained significantly elevated until 90 min of exercise. Skeletal muscle AMPK signaling, nNOSμ phosphorylation by AMPK, and total NOS activity increased to a similar extent in the two trials.

CONCLUSIONS:

The increase in glucose disposal after l-Arg infusion during exercise is likely due to the significantly higher plasma insulin concentration.

PMID:
21311355
DOI:
10.1249/MSS.0b013e318212a317
[Indexed for MEDLINE]
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