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Updated: Oct 1, 2026

In Vitro Assessment of Cardiac Function Using Skinned Cardiomyocytes
Published on: June 22, 2020
Calcium-independent activation of skinned cardiac muscle by secophalloidin
Anna E Bukatina1, Lou J Theodore, Kenneth B Campbell
1Departments of Anesthesiology, and Physiology and Biophysics, Mayo Foundation, Jo 4-184, 200 First Street SW, Rochester, MN 55905, USA. bukatina.anna@mayo.edu
Abstract:
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.
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