Post-exercise net protein synthesis in human muscle from orally
administered amino acids.
Tipton, Kevin D., Arny A. Ferrando, Stuart M. Phillips, David Doyle,
Jr., and Robert R. Wolfe.
Metabolism Unit, Shriners Burns Institute and Departments of
Surgery and Anesthesiology, University of Texas Medical Branch,
Galveston, TX 77550
APStracts 5:0272E, 1998.
We examined the response of net muscle protein synthesis to ingestion
of amino acids following an bout of resistance exercise. A primed,
constant infusion of ring-[2H5]phenylalanine was used to measure net
muscle protein balance in three male and three female volunteers on
three occasions. Subjects consumed, in random order, one L of: 1) a
mixed amino acid (40g) solution (MAA), 2) an essential amino acid
(40g) solution (EAA), and 3) a placebo solution (PLA). Arterial amino
acid concentrations increased [sim]150-640% above baseline during
ingestion of MAA and EAA. Net muscle protein balance was
significantly (p<0.05) increased from negative during PLA (-50_23
nmol(min -1(100mL leg volume-1 ) to positive during MAA (17_13
nmol(min -1(100mL leg volume-1 ) and EAA (29_14 nmol(min -1(100mL leg
volume-1). Since net balance was similar for MAA and EAA, it does not
appear necessary to include nonessential amino acids in a formulation
designed to elicit an anabolic response from muscle following
exercise. We conclude that ingestion of oral essential amino acids
results in a change from net muscle protein degradation to net muscle
protein synthesis following heavy resistance exercise in humans
similar to that seen when the amino acids were infused.
Received 18 August 1998; accepted in final form 30 November 1998.
APS Manuscript Number E378-8.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 18 December 1998