title: Electromechanical modulation of catabolic and anabolic pathways in chronically inactive, but neurally intact, muscles.
abstract: The extent and mechanisms by which neural input regulates skeletal muscle mass remain largely unknown. Adult spinal cord isolated (SI) rats were implanted unilaterally with a microstimulator, whereas the contralateral limb served as SI control (SI-C). A 100-HZ, 1-s stimulus was delivered every 30 s for 5 min, followed by a 5-min rest. This was repeated six times consecutively (SI-Stim1) or with a 9-h interval after the third bout (SI-Stim2) for 30 days (1 min of daily activity). SI-Stim1 and SI-Stim2 paradigms attenuated plantaris atrophy by 20% and 38%, respectively, whereas only SI-Stim2 blunted soleus atrophy (24%) relative to SI-C. Muscle mass changes occurred independent of the IGF-1/PI3K/Akt pathway. No relationships between SI or electromechanical stimulation and expression of several atrophy markers were observed. These data suggest that regulatory mechanisms for maintaining muscle mass previously shown in acute states of atrophy differ substantially from those observed in chronic states.
authors.affiliation: Department of Physiological Science, University of California, Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Jung A
authors.initials: JA
authors.lastname: Kim
authors.forename: Roland R
authors.initials: RR
authors.lastname: Roy
authors.forename: Soo J
authors.initials: SJ
authors.lastname: Kim
authors.forename: Hui
authors.initials: H
authors.lastname: Zhong
authors.forename: Fadia
authors.initials: F
authors.lastname: Haddad
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Baldwin
authors.forename: V Reggie
authors.initials: VR
authors.lastname: Edgerton
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001835:Body Weight / Q000502:physiology; D004247:DNA / Q000235:genetics; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D007537:Isometric Contraction / Q000502:physiology; D009121:Muscle Denervation; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism / Q000502:physiology*; D009133:Muscular Atrophy / Q000378:metabolism / Q000503:physiopathology; D009929:Organ Size / Q000502:physiology; D010812:Physical Stimulation; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000294:innervation / Q000502:physiology
chemical_list: D009124:Muscle Proteins; D012313:RNA; D004247:DNA