TY - JOUR
T1 - Adaptations in myosin heavy chain profile in chronically unloaded muscles.
AU - Talmadge, R. J.
AU - Roy, R. R.
AU - Bodine-Fowler, S. C.
AU - Pierotti, D. J.
AU - Edgerton, V. R.
PY - 1995
Y1 - 1995
N2 - In this review, myosin heavy chain (MHC) adaptations in response to several models of decreased neuromuscular activity (i.e. electrical activation and loading of a muscle) are evaluated. In each of these "reduced-activity" models it is important to: a) quantify the changes in electrical activation of the muscle as a result of the intervention; b) quantify the forces generated by the muscle; and c) determine whether the neuromuscular junction remains normal. Most of the models, including spaceflight, hindlimb suspension, spinal cord isolation, spinal cord transection, denervation, and limb immobilization in a shortened position, result in increases in the percentage of fast MHCs (or fast MHC mRNA) in normally slow rat muscles. It also can be inferred from histochemical data that increases in fast MHCs occur with TTX application and bed rest. The only "reduced-activity" model to consistently increase slow muscle myosin mRNA, and slow fibers is limb immobilization in a stretched position; however, this model results in at least a temporary increase in tension. It appears that the most common feature of these models that might induce MHC adaptations is the modification in loading rather than a change in the neuromuscular activity.
AB - In this review, myosin heavy chain (MHC) adaptations in response to several models of decreased neuromuscular activity (i.e. electrical activation and loading of a muscle) are evaluated. In each of these "reduced-activity" models it is important to: a) quantify the changes in electrical activation of the muscle as a result of the intervention; b) quantify the forces generated by the muscle; and c) determine whether the neuromuscular junction remains normal. Most of the models, including spaceflight, hindlimb suspension, spinal cord isolation, spinal cord transection, denervation, and limb immobilization in a shortened position, result in increases in the percentage of fast MHCs (or fast MHC mRNA) in normally slow rat muscles. It also can be inferred from histochemical data that increases in fast MHCs occur with TTX application and bed rest. The only "reduced-activity" model to consistently increase slow muscle myosin mRNA, and slow fibers is limb immobilization in a stretched position; however, this model results in at least a temporary increase in tension. It appears that the most common feature of these models that might induce MHC adaptations is the modification in loading rather than a change in the neuromuscular activity.
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M3 - Review article
C2 - 11539270
AN - SCOPUS:0029418636
SN - 1120-9992
VL - 5
SP - 117
EP - 137
JO - Basic and applied myology : BAM
JF - Basic and applied myology : BAM
IS - 2
ER -