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

Ulf Malmqvist, A Arner, R Makuch, R Dabrowska

Research output: Contribution to journalArticlepeer-review

Abstract

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.
Original languageEnglish
Pages (from-to)241-247
JournalPflügers Archiv
Volume432
Issue number2
DOIs
Publication statusPublished - 1996

Subject classification (UKÄ)

  • Pharmacology and Toxicology
  • Medicinal Chemistry

Keywords

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

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