Journal of Applied Physiology, Vol 75, Issue 3 1294-1299, Copyright © 1993 by American Physiological Society
Tenotomy and repair of latissimus dorsi muscles in rats: implications for transposed muscle grafts
V. A. Kadhiresan, P. J. Guelinckx and J. A. Faulkner
Department of Physiology, University of Michigan Medical School, Ann Arbor 48109-2007.
The functional properties of latissimus dorsi (LTD) muscles were evaluated
160 to 180 days after tenotomy and repair, when grafts had stabilized. Our
hypothesis was that, compared with control LTD muscles, LTD grafts would
develop less absolute force and power but that the specific force and
normalized power would not differ. Expressed as a percentage of the value
for control LTD muscles, values for grafts were 67% for muscle mass, 74%
for mean single fiber cross-sectional area, 56% for maximum absolute
isometric tetanic force, 64% for maximum absolute average force during
shortening, and 70% for maximum absolute power. Compared with control LTD
muscles, grafts showed no significant differences either in the number of
fibers in the total muscle cross section or in the optimum velocity for the
development of power. When force and power of grafts were normalized for
total fiber cross-sectional area and mass, respectively, only the value for
maximum specific force (84% of control value) was significant. The
mechanisms responsible for the decrease in specific force after tenotomy
and repair are not known. In contrast to the deficit in maximum specific
force, the 30% deficit in maximum absolute power of grafts compared with
control LTD muscles was explained completely by the 33% smaller muscle
mass.
