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Effect of strain on actomyosin kinetics in isometric muscle fibers

Siththanandan, VB; Donnelly, JL; Ferenczi, MA

Authors

VB Siththanandan

JL Donnelly

MA Ferenczi



Abstract

Investigations were conducted into the biochemical and mechanical states of cross-bridges during isometric muscle contraction. Rapid length steps (3 or 6 nm hs–1) were applied to rabbit psoas fibers, permeabilized and isometric, at either 12°C or 20°C. Fibers were activated by photolysis of P3-1-(2-nitrophenyl)-ethyl ester of ATP infused into rigor fibers at saturating Ca2+. Sarcomere length, tension, and phosphate release were recorded—the latter using the MDCC-PBP fluorescent probe. A reduction in strain, induced by a rapid release step, produced a short-lived acceleration of phosphate release. Rates of the phosphate transient and that of phases 3 and 4 of tension recovery were unaffected by step size but were elevated at higher temperatures. In contrast the amplitude of the phosphate transient was smaller at 20°C than 12°C. The presence of 0.5 or 1.0 mM added ADP during a release step reduced both the rate of tension recovery and the poststep isometric tension. A kinetic scheme is presented to simulate the observed data and to precisely determine the rate constants for the elementary steps of the ATPase cycle.

Citation

Siththanandan, V., Donnelly, J., & Ferenczi, M. (2006). Effect of strain on actomyosin kinetics in isometric muscle fibers. Biophysical Journal, 90(10), 3653-3665. https://doi.org/10.1529/biophysj.105.072413

Journal Article Type Article
Publication Date May 1, 2006
Deposit Date Feb 12, 2009
Journal Biophysical Journal
Print ISSN 0006-3495
Electronic ISSN 1542-0086
Publisher Biophysical Society
Peer Reviewed Peer Reviewed
Volume 90
Issue 10
Pages 3653-3665
DOI https://doi.org/10.1529/biophysj.105.072413