LE3 .A278 2004

2004

Murphy, René

Acadia University

Bachelor of Science

Honours

Biology

Biology

A reduction in muscle mass is known to occur following spinal cord transection. Passive cycling exercise training has been shown to ameliorate or reverse these effects. The aims of this study were to examine the acute effects of spinal cord transection and motor driven cycling exercise training on muscle mass, total and myofibrillar protein content, cytochrome C oxidase ( CYTOX) activity, and ß- adrenergic receptor ( ß- AR) density of skeletal muscle. Female Sprague- Dawley rats ( n= 43; ~ 250g) were randomly assigned to 5 experimental groups: control 4 day; control 8 day; spinal cord transection ( Tx) 4 day; spinal cord transection 8 day; and spinal cord transection with exercise. A complete spinal cord transection was performed surgically at the T10 cord level. Exercise training on motor driven bicycles was initiated 5 days after Tx and occurred 60 min/ day for 3 days. Compared to controls, Tx resulted in a marked decrease in muscle mass, with no significant change in total and myofibrillar protein concentrations. Spinal cord transection also resulted in a significant decrease in plantaris CYTOX activity. ß-adrenergic receptor density of the lateral gastrocnemius was unchanged following spinal cord transection, however the ß- AR density of the triceps was found to increase. Exercise for 3 days was not effective in preventing or reversing the acute effects of spinal cord transection. Our results suggest that: 1) muscle atrophy occurs rapidly in the first 8 days following Tx; 2) this atrophy is due to changes in protein content; 3) CYTOX activity decreases rapidly following Tx; 4) ß- AR density is increased in the triceps but unchanged in the lateral gastrocnemius 8 days after Tx; and 5) although exercise training has previously been shown to be effective, 3 bouts of cycling exercise, as administered in this study, did not counter the acute effects of Tx on hindlimb skeletal muscle properties.

The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.

https://scholar.acadiau.ca/islandora/object/theses:432