Mass and fiber cross-sectional area of soleus muscle grafts following training.
This study tested the hypothesis that endurance training initiated 28 d following grafting of the soleus muscle would increase fiber cross-sectional area concomitant with an increase in mass. Nerve-implant orthotopic grafting operations were performed on 6-wk-old rats anesthetized with pentobarbital sodium. A cohort of animals began running 28 d later. Control muscles were from age-matched, untrained rats. Mass and fiber cross-sectional area of grafts were 37 and 66% less than the respective control values at both 56 and 112 d post-grafting. Training increased graft mass by 49% over the non-run graft value of 82 +/- 8 mg at 56 d post-grafting. Continued training did not increase mass further. The grafts of trained rats were 33% greater than untrained at day 112 due to growth of grafts in untrained rats. Running had no effect on fiber cross-sectional area of grafts through 56 d, but by 112 d the cross-sectional area of Type I fibers was 30% greater than the non-run graft value of 1,271 +/- 81 micron2. By 112 d fiber type profiles were not different between control muscle and grafts from trained and untrained rats. We conclude that there is a dissociation between mass and fiber cross-sectional area in grafts compared to control muscle, and training affects these variables by similar magnitudes but at different times.
Clark
K I
KI
Department of Kinesiology, University of Michigan, Ann Arbor 48109-2214.
Morales
P G
PG
White
T P
TP
D000818:Animals; D005260:Female; D009132:Muscles / Q000033:anatomy & histology* / Q000637:transplantation; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D051381:Rats; D011919:Rats, Inbred Strains; D014182:Transplantation, Autologous