Ca(2+)-force relationship of frog skeletal muscle: a dynamic model for parameter estimation.
A simple mathematical model describing the dynamic connection between Ca2+ and force generation in intact skeletal muscle from the frog has been developed from isometric force responses to cytosolic Ca2+ 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 (f(app)) and the fractional rate of cross-bridge detachment (g*). While g* is constant, f(app) 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 Ca2+ 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 Ca2+ 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 Ca2+ and force.
Shames
D M
DM
Department of Medicine (Cardiology), University of California, San Francisco 94143, USA.
Baker
A J
AJ
Weiner
M W
MW
Camacho
S A
SA
D000818:Animals; D001001:Anura; D002118:Calcium / Q000502:physiology*; D008954:Models, Biological; D008962:Models, Theoretical; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*
D002118:Calcium