Myosin heavy chain isoform and ubiquitin protease mRNA expression after passive leg cycling in persons with spinal cord injury.
OBJECTIVE
To determine the effects of passive leg cycling exercise on myosin heavy chain (MHC) isoform and ubiquitin (UBI) protease mRNA expression in patients with spinal cord injury (SCI).


METHODS
Case series.


METHODS
Eight SCI subjects (5 men, 3 women) participated in a 12-week exercise program involving the Psycle ergometer. Training occurred 2 days a week at 75% of each subject's maximum heart rate. Anthropometric measures (body weight, thigh girth, and body mass index) and muscle biopsy specimens were obtained before and after training. Analyses were performed to determine the mRNA expression of types I, IIa, and IIx MHC, as well as UBI, a UBI-conjugating enzyme (E2), and 20S proteasome (20S).


RESULTS
Despite small increases, paired t tests (p < .05) to assess changes from pretraining to posttraining failed to locate significant differences for the three anthropometric measures. For mRNA expression, there were significant increases in expression of MHC types IIa and IIx and significant decreases in expression for UBI, E2, and 20S.


CONCLUSIONS
Exercise using passive leg cycling increases the expression of fast MHC isoforms while concomitantly decreasing proteolytic activity associated with muscle degradation, thus helping to possibly ameliorate muscle atrophy in patients with SCI.
Willoughby
D S
DS
Department of Kinesiology, Texas Christian University, Fort Worth 76129, USA.
Priest
J W
JW
Jennings
R A
RA
D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000235:genetics; D000293:Adolescent; D000328:Adult; D001706:Biopsy; D015992:Body Mass Index; D003546:Cysteine Endopeptidases / Q000096:biosynthesis / Q000235:genetics; D010450:Endopeptidases / Q000096:biosynthesis / Q000235:genetics*; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology; D008025:Ligases / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009097:Multienzyme Complexes / Q000096:biosynthesis / Q000235:genetics; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000534:rehabilitation; D044763:Ubiquitin-Conjugating Enzymes; D064570:Ubiquitin-Specific Proteases
D009097:Multienzyme Complexes; D020033:Protein Isoforms; D012333:RNA, Messenger; D044763:Ubiquitin-Conjugating Enzymes; D010450:Endopeptidases; D064570:Ubiquitin-Specific Proteases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains; D008025:Ligases