A comparison of rat myosin from fast and slow skeletal muscle and the effect of disuse

Unsworth, B. R.; Witzmann, F. A.; Fitts, R. H.

Certain enzymatic and structural features of myosin, purified from rat skeletal muscles representative of the fast twitch glycolytic (type IIb), the fast twitch oxidative (type IIa), and the slow twitch oxidative (type I) fiber, were determined and the results were compared with the measured contractile properties. Good correlation was found between the shortening velocities and Ca(2+)-activated ATPase activity for each fiber type. Short term hind limb immobilization caused prolongation of contraction time and one-half relaxation time in the fast twitch muscles and a reduction of these contractile properties in slow twitch soleus. Furthermore, the increased maximum shortening velocity in the immobilized soleus could be correlated with increased Ca(2+)-ATPase, but no change was observed in the enzymatic activity of the fast twitch muscles. No alteration in light chain distribution with disuse was observed in any of the fiber types. The myosin from slow twitch soleus could be distinguished from fast twitch myosins on the basis of the pattern of peptides generated by proteolysis of the heavy chains. Six weeks of hind limb immobilization resulted in both an increased ATPase activity and an altered heavy chain primary structure in the slow twitch soleus muscle.

Document ID

19850009201

Acquisition Source

Legacy CDMS

Document Type

Reprint (Version printed in journal)

Authors

Date Acquired

September 5, 2013

Publication Date

July 14, 1981

Subject Category

Report/Patent Number

Accession Number

85N17510

Funding Number(s)

Distribution Limits

Public

Work of the US Gov. Public Use Permitted.

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