Exogenous calmodulin increases Ca2+ sensitivity of isometric tension activation and myosin phosphorylation in skinned smooth muscle

P. S. Cassidy, W. G.L. Kerrick, P. E. Hoar, D. A. Malencik

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

We have investigated the effect of exogenous calmodulin on chicken gizzard or rabbit ileum smooth muscle functionally skinned by mechanical grinding or exposure to Triton X-100 detergent. We found that a specific protein inhibitor, modulator binding protein, caused a loss of Ca2+-activated tension which was restored by subsequent treatment with calmodulin. Calmodulin at 5 μM increased 10-fold the speed of development of isometric tension while it had no significant effect on the rate of relaxation or on maximum tension at high Ca2+ concentrations. The Ca2+ sensitivity of steady state tension and LC20 phosphorylation were also increased by 5 μM calmodulin. These results are consistent with a calmodulin-regulated light chain kinase/phosphatase system being responsible for activation of tension in smooth muscle.

Original languageEnglish (US)
Pages (from-to)115-120
Number of pages6
JournalPflügers Archiv European Journal of Physiology
Volume392
Issue number2
DOIs
StatePublished - Dec 1 1981
Externally publishedYes

Keywords

  • Calmodulin
  • Myosin phosphorylation
  • Skinned smooth muscle

ASJC Scopus subject areas

  • Physiology

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