Myosin light chain phosphorylation in fast and slow skeletal muscles in situ.

R. L. Moore, J. T. Stull

Research output: Contribution to journalArticle

205 Citations (Scopus)

Abstract

The physiological properties of contraction-induced phosphate incorporation into the phosphorylatable light chain (P-light chain) of myosin were examined in fast-twitch white, fast-twitch red, and slow-twitch skeletal muscles in situ. Neural stimulation of rat gastrocnemius muscles between 0.5 and 100 Hz produced an increase in the phosphate content of the P-light chain from the white portion of the muscle, and the rate of P-light chain phosphorylation was frequency dependent. The extent of phosphorylation of P-light chain from the fast-twitch red portion of the gastrocnemius muscle was less. In contrast to fast-twitch skeletal muscle, only high-frequency stimulation (30-100 Hz) produced a small increase in the phosphate content of P-light chain from the slow-twitch soleus muscle. Fast white muscle contained 2.2 and 3.5 times more myosin light chain kinase activity than did the fast red and slow muscle, respectively. The rate of P-light chain dephosphorylation was four times faster in slow muscle than in fast white muscle. Thus the greater extent of phosphorylation of P-light chain in fast-twitch white skeletal muscle fibers may be due in part to the presence of more kinase and less phosphatase activities. Isometric twitch tension potentiation was correlated to the extent of phosphorylation of P-light chain from fast white muscle. The physiological consequences of P-light chain phosphorylation are likely to be of greatest importance in fast-twitch white muscle.

Original languageEnglish (US)
JournalThe American journal of physiology
Volume247
Issue number5 Pt 1
StatePublished - Nov 1984

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Myosin Light Chains
Skeletal Muscle
Phosphorylation
Light
Muscles
Phosphates
Fast-Twitch Muscle Fibers
Myosin-Light-Chain Kinase
Skeletal Muscle Fibers
Phosphoric Monoester Hydrolases
Phosphotransferases

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Myosin light chain phosphorylation in fast and slow skeletal muscles in situ. / Moore, R. L.; Stull, J. T.

In: The American journal of physiology, Vol. 247, No. 5 Pt 1, 11.1984.

Research output: Contribution to journalArticle

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