Protein kinase C increases force and slows relaxation in smooth muscle: Evidence for regulation of the myosin light chain phosphatase

Mitsuo Ikebe, Frank V. Brozovich

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

To determine if activation of protein kinase C (PKC) participates in the molecular mechanism for agonist induced force enhancement, force was measured in single β-escin skinned smooth muscle cells stimulated to contract with Ca2+, myosin light chain (MLC) kinase, PKC and microcystin-LR. The constituently active fragment of protein kinase C (PKM) increased both force and MLC phosphorylation in cells previously stimulated to contract at submaximal Ca2+. For cells contracted with saturating Ca2+, PKM stimulation did not increase either force or MLC phosphorylation. For contractions stimulated with both PKM and microcystin-LR, force rose significantly slower than contractions produced by Ca2+ or MLC kinase, suggesting that PKM increases force by a decrease in the rate of myosin dephosphorylation. Consistent with this hypothesis is the finding that the rate of force relaxation was slowed by PKM. This is the first direct demonstration that activation of PKC increases force in smooth muscle, and these results suggest that in smooth muscle, agonist induced activation of PKC plays a role in force regulation via an inhibition of myosin light chain phosphatase activity.

Original languageEnglish (US)
Pages (from-to)370-376
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume225
Issue number2
DOIs
StatePublished - Aug 14 1996
Externally publishedYes

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Myosin-Light-Chain Phosphatase
Protein Kinase C
Smooth Muscle
Muscle
Myosin-Light-Chain Kinase
Myosin Light Chains
Phosphorylation
Chemical activation
Escin
Myosins
Smooth Muscle Myocytes
Demonstrations
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Protein kinase C increases force and slows relaxation in smooth muscle : Evidence for regulation of the myosin light chain phosphatase. / Ikebe, Mitsuo; Brozovich, Frank V.

In: Biochemical and Biophysical Research Communications, Vol. 225, No. 2, 14.08.1996, p. 370-376.

Research output: Contribution to journalArticle

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