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Factors affecting muscle fiber transformation in cross. Reinnervated muscle
Author(s) -
Thomas P. E.,
Rantunga K. W.
Publication year - 1993
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880160213
Subject(s) - reinnervation , myosin , gene isoform , chemistry , anatomy , fiber type , soleus muscle , medicine , endocrinology , skeletal muscle , biology , biochemistry , gene
Abstract Nerves of two fast muscles [peroneus longus (PL) and extensor digitorum longus (EDL)], having different type 2 muscle fiber compositions, were used to cross‐reinnervate the slow soleus muscle in the rat. Contraction characteristics, histochemical muscle fiber type compsotions and myosin heavy chain (MHC) isoform compositions were determined for the reinnervated muscles. Shortening velocity increased in soleus muscles crossreinnervated with EDL nerve [X‐SOL(EDL)] but not in muscles cross‐reinnervated with PL nerve [X‐SOL(PL)]. Type 2A MHC isoform content was increased in X‐SOL(EDL) but not in X‐SOL(PL), where MHC isoform composition remained similar to normal soleus. The complement of type 1 (slow) muscle fibers was reduced and that of type 2 (fast) fibers increased in both types of X‐SOL muscle, but this change was significantly greater in X‐SOL(EDL); the majority of the type 2 fibers in X‐SOL muscles were of type 2A. Results show that “the type 2 composition” of the reinnervating motoneuron pool is an important factor in determining the transformation of a target slow muscle after cross‐reinnervation. © 1993 John Wiley & Sons, Inc.