Calcium-independent activation of skinned cardiac muscle by secophalloidin

Anna E. Bukatina, Lou J. Theodore, Kenneth B. Campbell, Gary C. Sieck

Research output: Contribution to journalArticle

3 Scopus citations


Thin filament regulation of muscle contraction is believed to be mediated by both Ca2+ and strongly bound myosin cross-bridges. We found that secophalloidin (SPH, 5-8 mM) activates cross-bridge cycling without Ca2+ causing isometric force comparable to that induced by Ca2+. At saturated [SPH], Ca2+ further increased force by 20%. SPH-induced force was reversible upon washing with a relaxing solution. However, there was more than 30% irreversible loss in subsequent Ca2+-activated force. We hypothesize that SPH activates muscle via strongly bound cross-bridges. SPH-activated contraction provides a new model for studying the role of Ca2+ and cross-bridges in muscle regulation.

Original languageEnglish (US)
Pages (from-to)201-204
Number of pages4
JournalFEBS Letters
Issue number1-3
StatePublished - May 22 2002



  • Activation
  • Cardiac muscle
  • Contraction
  • Regulation
  • Secophalloidin

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

Bukatina, A. E., Theodore, L. J., Campbell, K. B., & Sieck, G. C. (2002). Calcium-independent activation of skinned cardiac muscle by secophalloidin. FEBS Letters, 519(1-3), 201-204.