Abstract |
The slow tonic anterior latissimus dorsi (ALD) muscle of the chicken contains two isomyosins, namely SM-1 and SM-2. The proportions of the two isoforms change with age, SM-2 expression increasing at the expense of SM-1. Applying a load on the wing increases the rate and extent of SM-1 replacement. Here we have demonstrated that decreasing the load by removal of the distal portion of the wing in 1-week-old chickens had an effect opposite to that of overloading in that it slowed muscle growth and the rate of SM-1 elimination. Experimental unloading of muscles previously weighted for 1 or 3 weeks slowed the growth rate of muscles, with consequent regression of relative hypertrophy; however, it did not lead to the reexpression of SM-1 myosin. This indicates that the overload-induced changes in myosin expression are not readily reversible. Nerve section produced unexpected results, in that it advanced the normal developmental shift in myosin expression toward predominance of the SM-2 isoform, similar to the effect of muscle overload.
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Authors | S K Reid, J M Kennedy, N Shimizu, A Stewart, G Vrbova, R Zak |
Journal | The Biochemical journal
(Biochem J)
Vol. 260
Issue 2
Pg. 449-54
(Jun 01 1989)
ISSN: 0264-6021 [Print] England |
PMID | 2764882
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
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Topics |
- Animals
- Chickens
- Gene Expression Regulation
- Isomerism
- Muscle Denervation
- Myosins
(genetics)
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