The calcium-force relationship of frog skeletal muscle: a dynamic
model for parameter estimation.
Shames, David M., Anthony J. Baker, Michael W. Weiner, and S. Albert
Camacho.
Cardiovascular Research Institute, the Departments of Medicine
(Cardiology) and Radiology, University of California, San Francisco,
and the Magnetic Resonance Unit, Department of Veterans Affairs
Medical Center, San Francisco, CA 94121
APStracts 3:0240C, 1996.
A simple mathematical model describing the dynamic connection between
calcium and force generation in intact skeletal muscle from the frog
has been developed from isometric force responses to cytosolic
calcium concentration ([Ca2+]c) transients during tetanic and twitch
contractions. The main element of the model is a two state cross
-bridge cycle characterized by the fractional rate of cross-bridge
attachment, fapp, and the fractional rate of cross-bridge detachment,
g*. While g* is constant, fapp is time-varying and regulated by both
[Ca2+]c and force. Having only four adjustable parameters, the model
is mathematically unique, thereby allowing precise parameter
estimation from the dynamic calcium and force data. The model should
be useful for developing insights into the relative importance for
force generation and relaxation of 1) the size and shape of the
calcium transient, 2) the sensitivity of the fractional rate of
cross-bridge attachment to both the [Ca2+]c and the force responses
and 3) the fractional rate of cross-bridge detachment which is
insensitive to both calcium and force.
Received 27 November 1995; accepted in final form 12 June 1996.
APS Manuscript Number C709-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996