Effect of neonatal denervation-reinnervation on the functional capacity of a 129ReJ dy/dy murine dystrophic muscle.
The sciatic nerves of 14-day-old 129 ReJ normal (++) and dystrophic (dy/dy) mice were transected in the mid-thigh region. The cut ends of the nerves were approximated to facilitate regeneration. One hundred days after denervation, contractile properties of denervated-reinnervated, normal and dystrophic extensor digitorum longus (EDL) muscles were compared to age-matched normal and dystrophic muscles. In dystrophic muscle, in vitro twitch and tetanic tensions were reduced, compared to those of normal muscle. The denervation-reinnervation procedure resulted in an increase in these parameters as compared to unoperated dy muscle. These data correlated with increases in total myofiber cross-sectional areas. Twitch contraction time was not significantly affected by the dystrophic condition or by the denervation-reinnervation protocol. Whereas dystrophic muscle had a longer half-relaxation time than normal muscle, denervation-reinnervation of the dystrophic EDL resulted in a significantly faster half-relaxation time. While fatigue resistance was greater in dystrophic muscles than in normal muscle, there was a significant decrease in fatigue resistance in the denervated-reinnervated dystrophic muscle. Transient neonatal denervation results in modification of both the morphological and physiological characteristics of murine dystrophy.
Hermanson
J W
JW
Department of Neurobiology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
Moschella
M C
MC
Ontell
M
M
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D008854:Microscopy, Electron; D009119:Muscle Contraction; D009121:Muscle Denervation; D009132:Muscles / Q000473:pathology / Q000503:physiopathology* / Q000648:ultrastructure; D009137:Muscular Dystrophy, Animal / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D009416:Nerve Regeneration