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Fast‐to‐slow transformation in stimulated rat muscle
Author(s) -
Jarvis Jonathan C.,
Mokrusch Thomas,
Kwende Martin M.N.,
Sutherland Hazel,
Salmons Stanley
Publication year - 1996
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/(sici)1097-4598(199611)19:11<1469::aid-mus11>3.0.co;2-o
Subject(s) - stimulation , myosin , hindlimb , gene isoform , anatomy , skeletal muscle , biology , muscle contraction , endocrinology , medicine , chemistry , gene , microbiology and biotechnology , biochemistry
Several previous studies have failed to demonstrate changes due to chronic stimulation in contractile speed of innervated fast rat muscles, and it has been suggested that the adaptive capacity of skeletal muscle in this species is limited. We have reassessed this contention. Fast muscles of the rat hind limb were stimulated continuously at 10 or 20 Hz for 55–61 days. The maximum shortening velocity of the extensor digitorum longus muscles was reduced to 50% of the control value. The proportion of type 1 fibers increased from 4% in control muscle to 34% in stimulated muscles and there was a corresponding reduction in type 2B/D fibers. The proportion of type 2A fibers after stimulation was similar to that in control muscles. These results, taken together with our published analyses of myosin isoform composition of these muscles, show that the mechanisms that control gene expression in response to activity are not exclusive to larger mammals. © 1996 John Wiley & Sons, Inc.