title: Early effects of spinal cord transection on skeletal muscle properties.
abstract: Modulation of beta-adrenergic receptor (beta-AR) activity affects muscle mass and could have a role in the reduction of muscle mass observed following spinal cord transection (Tx). The aims of this study were to examine the early acute effects of Tx on muscle mass, total and myofibrillar protein concentrations, cytochrome c oxidase activity, and beta-AR density of skeletal muscle, to ascertain if any change in muscle properties could be related to beta-AR signalling events. Female Sprague-Dawley rats (n = 33; approximately 255 g) were randomly assigned to 4 experimental groups: control 4 d, control 8 d, Tx 4 d, and Tx 8 d. A complete Tx was performed surgically at the T10 cord level. Compared with controls, muscle mass and muscle - body mass ratios decreased significantly following Tx, with no significant change observed in total and myofibrillar protein concentrations. Spinal cord Tx also resulted in a significant decrease in plantaris cytochrome c oxidase activity by 24% at Tx 4 d and 28% at Tx 8 d (p < 0.05). Beta-AR density of the lateral gastrocnemius was unchanged; however, the beta-AR density of the forelimb triceps brachii m. was found to increase after Tx. Our results suggest that changes in muscle mass and cytochrome c oxidase activity rapidly occur after Tx and do not appear to be related to changes in beta-AR density.
authors.affiliation: Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada.
authors.forename: Melissa D
authors.initials: MD
authors.lastname: Kelley
authors.forename: Satra
authors.initials: S
authors.lastname: Nim
authors.forename: Guy
authors.initials: G
authors.lastname: Rousseau
authors.forename: Jonathon R
authors.initials: JR
authors.lastname: Fowles
authors.forename: René J L
authors.initials: RJ
authors.lastname: Murphy
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000503:physiopathology*; D009133:Muscular Atrophy / Q000209:etiology* / Q000503:physiopathology; D009210:Myofibrils / Q000737:chemistry; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000502:physiology; D015398:Signal Transduction; D013116:Spinal Cord / Q000601:surgery; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*
chemical_list: D009124:Muscle Proteins; D011943:Receptors, Adrenergic, beta; D003576:Electron Transport Complex IV