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The effects of caldesmon extraction on mechanical properties of skinned smooth muscle fibre preparations

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Author

Summary, in English

The role of caldesmon in the regulation of smooth muscle contraction was investigated in chemically skinned smooth muscle fibres from the guinea-pig taenia coli. A 19-kDa C-terminal fragment of caldesmon gave a minor (<5%) reduction of force in fully thiophosphorylated fibres, but reduced force by about 50% at intermediate activation levels without affecting the level of light chain phosphorylation. An extraction procedure was developed using incubation in solutions containing high Mg2+ concentrations. Protein analysis revealed a selective decrease in the amount of caldesmon in the fibres. Maximal active force per cross-sectional area was unaffected. The Ca2+ dependence of active force was shifted towards lower Ca2+ concentrations and became less steep. The effects of extraction of caldesmon could in part be reversed by incubation in a solution containing purified caldesmon. The results are consistent with the hypothesis that caldesmon in smooth muscle thin filaments inhibits force generation and plays a role in regulating cooperative attachment of cross-bridges at sub-maximal levels of activation in smooth muscle.

Publishing year

1996

Language

English

Pages

241-247

Publication/Series

Pflügers Archiv

Volume

432

Issue

2

Document type

Journal article

Publisher

Springer

Topic

  • Pharmacology and Toxicology
  • Medicinal Chemistry

Keywords

  • Skinned smooth muscle
  • Caldesmon
  • 19-kDa fragment
  • Calcium sensitivity

Status

Published

ISBN/ISSN/Other

  • ISSN: 0031-6768