Electrical stimulation of denervated muscles of rats maintains mass and force, but not recovery following grafting.
OBJECTIVE
Denervated skeletal muscles lack contractile activity and subsequently lose mass and force generation. Prolonged periods of denervation prior to nerve-implant grafting limit the recovery of mass and force. We hypothesized that electrical stimulation during a period of denervation that maintains mass and force above the levels of denervated muscles enhances the recovery of mass and force following nerve-implant grafting.


METHODS
The extensor digitorum longus (EDL) muscles of anesthetized rats were denervated, and a stimulator was implanted. Following 4 or 7 months of denervation, with or without electrical stimulation, the EDL muscles were removed, evaluated in vitro for mass and contractile properties, and then nerve-implant grafted into syngeneic rats. Unoperated, contralateral muscles were also evaluated and grafted.


RESULTS
The hypothesis was not supported by the experimental data. Compared with values for 4- or 7-month denervated muscles, the stimulated-denervated muscles maintained higher mass and force, less prolonged time-to-peak tensions and half-relaxation times, and higher excitability. Nevertheless, the recovery of mass and force following grafting was not improved.


CONCLUSIONS
The factors within long-term denervated muscles that hinder recovery following grafting appear to be related primarily to factors associated with the duration of denervation and not to the level of atrophy and weakness prior to grafting.
Dow
Douglas E
DE
Institute of Gerontology, University of Michigan, Ann Arbor, Michigan 48109-2007, USA.
Carlson
Bruce M
BM
Hassett
Cheryl A
CA
Dennis
Robert G
RG
Faulkner
John A
JA
D000818:Animals; D004558:Electric Stimulation / Q000379:methods*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000502:physiology / Q000528:radiation effects; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000294:innervation* / Q000473:pathology / Q000503:physiopathology; D009133:Muscular Atrophy / Q000209:etiology* / Q000628:therapy*; D016377:Organ Transplantation / Q000379:methods*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors