Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise

• Published in: American journal of physiology: endocrinology and metabolism Vol. 287; no. 1; pp. E1 - E7
• Main Authors: Karlsson, Hakan K. R, Nilsson, Per-Anders, Nilsson, Johnny, Chibalin, Alexander V, Zierath, Juleen R, Blomstrand, Eva
• Format: Journal Article
• Language: English
• Published: United States 01.07.2004
• Subjects: Administration, Oral; Adult; Amino Acids, Branched-Chain - administration & dosage; Amino Acids, Branched-Chain - metabolism; Exercise - physiology; Exercise Test - methods; Humans; Insulin - blood; Male; MEDICIN; Medicin och hälsovetenskap; MEDICINE; Muscle, Skeletal - physiology; Phosphorylation; Physical Endurance - physiology; Ribosomal Protein S6 Kinases, 70-kDa - metabolism; Signal Transduction - physiology
• ISSN: 0193-1849; 1522-1555; 1522-1555
• DOI: 10.1152/ajpendo.00430.2003

1 Department of Health and Sport Sciences, University College of Physical Education and Sports, Stockholm S-114 86; 2 Section Integrative Physiology, Department of Surgical Sciences, Karolinska Institute, Stockholm, S-171 77; and 3 Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, S-171 76, Sweden Submitted 25 September 2003 ; accepted in final form 24 February 2004 ABSTRACT The aim of the study was to investigate the effect of resistance exercise alone or in combination with oral intake of branched-chain amino acids (BCAA) on phosphorylation of the 70-kDa S6 protein kinase (p70 S6k ) and mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK1/2), and p38 MAPK in skeletal muscle. Seven male subjects performed one session of quadriceps muscle resistance training (4 x 10 repetitions at 80% of one repetition maximum) on two occasions. In a randomized order, double-blind, crossover test, subjects ingested a solution of BCAA or placebo during and after exercise. Ingestion of BCAA increased plasma concentrations of isoleucine, leucine, and valine during exercise and throughout recovery after exercise (2 h postexercise), whereas no change was noted after the placebo trial. Resistance exercise led to a robust increase in p70 S6k phosphorylation at Ser 424 and/or Thr 421 , which persisted 1 and 2 h after exercise. BCAA ingestion further enhanced p70 S6k phosphorylation 3.5-fold during recovery. p70 S6k phosphorylation at Thr 389 was unaltered directly after resistance exercise. However, during recovery, Thr 389 phosphorylation was profoundly increased, but only during the BCAA trial. Furthermore, phosphorylation of the ribosomal protein S6 was also increased in the recovery period only during the BCAA trial. Exercise led to a marked increase in ERK1/2 and p38 MAPK phosphorylation, which was completely suppressed upon recovery and unaltered by BCAA. In conclusion, BCAA, ingested during and after resistance exercise, mediate signal transduction through p70 S6k in skeletal muscle. exercise training; mitogen-activated protein kinase; protein synthesis; signal transduction Address for reprint requests and other correspondence: E. Blomstrand, Univ. College of Physical Education and Sports, Box 5626, S-114 86 Stockholm, Sweden (E-mail: eva.blomstrand{at}ihs.se ).