Changes in electrical response function and myosin heavy chain isoforms following denervation and reinnervation of bilateral posterior cricoarytenoid muscles in dogs

Abstract

Denervation produced up-regulation of MyHC-1 and MyHC-Neonatal messenger ribonucleic acid (mRNA) expression. Reinnervation caused a decrease of MyHC-2X mRNA expression. The electrical voltage threshold of vocal fold movement and maximum abduction of denervation were greater than that of the reinnervated or control group. The denervated vocal abduction maximum of response to electrical stimulation was less than that in reinnervation or control groups.

Functional electrical stimulation following nerve injury in a large animal model

“…23,44 The specific morphometric changes of laryngeal muscles after denervation and reinnervation seem to be species-specific, with a reduction of type I fibers in rats and an increase in dogs. [45][46][47] The innervated equine PCA has 30-40% type I fibers, 21 while in this study the reinnervated PCA after RLn axonotmesis demonstrated a higher proportion of type I fibers (>50%), with the highest value in the stimulated group suggesting a positive effect of FES on these fibers. These findings confirm a preferential denervation atrophy of type II fibers and increase in type I fibers after reinnervation possibly as a result of sprouting from slow axons as reported after other peripheral nerve injuries in different species.…”

“…This dependence of fiber type expression upon neural input is also evident in the equine PCA that shows an increase in type IIx fibers after complete denervation and a marked reduction in type I fiber after progressive denervation induced by idiopathic recurrent laryngeal neuropathy . The specific morphometric changes of laryngeal muscles after denervation and reinnervation seem to be species‐specific, with a reduction of type I fibers in rats and an increase in dogs . The innervated equine PCA has 30‐40% type I fibers, while in this study the reinnervated PCA after RLn axonotmesis demonstrated a higher proportion of type I fibers (>50%), with the highest value in the stimulated group suggesting a positive effect of FES on these fibers.…”