Acute molecular responses of skeletal muscle to resistance exercise in able-bodied and spinal cord-injured subjects

• Published in: Journal of applied physiology (1985) Vol. 94; no. 6; pp. 2255 - 2262
• Main Authors: Bickel, C. Scott, Slade, Jill M, Haddad, Fadia, Adams, Gregory R, Dudley, Gary A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.06.2003; American Physiological Society
• Subjects: Adult; Biological and medical sciences; Case-Control Studies; Cyclin-Dependent Kinase Inhibitor p21; Cyclins - genetics; Electric Stimulation; Exercise; Female; Health problems; Humans; Insulin; Insulin-Like Growth Factor Binding Protein 4 - genetics; Insulin-Like Growth Factor Binding Protein 5 - genetics; Leg; Male; Medical sciences; Muscle, Skeletal - metabolism; Muscles; Muscular system; Myogenin - genetics; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Osmolar Concentration; Osteoporosis; Proteins; RNA, Messenger - metabolism; Spinal cord injuries; Spinal Cord Injuries - physiopathology; Weight Lifting; Human; Nervous system diseases; mechano-growth factor; insulin-like growth factor I; Motor system disorder; myogenin; Electrical stimulus; Insulin like growth factor 1; Striated muscle; Metabolism; Long term; Atrophy; Insulin like growth factor binding protein; Central nervous system disease; Spinal cord disease; insulin- like growth factor binding protein; Response stimulus relation; Non-programmatic
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00014.2003

1  Department of Exercise Science, University of Georgia, Athens, Georgia 30602; 3  Department of Physiology and Biophysics, University of California, Irvine, California 92697-4560; and 2  Shepherd Center, Atlanta, Georgia 30309 Spinal cord injury (SCI) results in muscle atrophy, which contributes to a number of health problems, such as cardiovascular deconditioning, metabolic derangement, and osteoporosis. Electromyostimulation (EMS) holds the promise of ameliorating SCI-related muscle atrophy and, therefore, improving general health. To date, EMS training of long-term SCI subjects has resulted in some muscle hypertrophy but has fallen short of normalizing muscle mass. The aim of this study was to compare the molecular responses of vastus lateralis muscles from able-bodied (AB) and SCI subjects after acute bouts of EMS-induced resistance exercise to determine whether SCI muscles displayed some impairment in response. Analysis included mRNA markers known to be responsive to increased loading in rodent muscles. Muscles of AB and SCI subjects were subjected to EMS-stimulated exercise in two 30-min bouts, separated by a 48-h rest. Needle biopsy samples were obtained 24 h after the second exercise bout. In both the AB and SCI muscles, significant changes were seen in insulin-like growth factor binding proteins 4 and 5, cyclin-dependent kinase inhibitor p21, and myogenin mRNA levels. In AB subjects, the mRNA for mechano-growth factor was also increased. Before exercise, the total RNA concentration of the SCI muscles was less than that of the AB subjects but not different postexercise. The results of this study indicate that acute bouts of resistance exercise stimulate molecular responses in the skeletal muscles of both AB and SCI subjects. The responses seen in the SCI muscles indicate that the systems that regulate these molecular responses are intact, even after extended periods of muscle unloading. mechano-growth factor; insulin-like growth factor I; insulin-like growth factor binding protein; myogenin