Ca(2+)-force relationship of frog skeletal muscle: a dynamic model for parameter estimation

Am J Physiol. 1996 Dec;271(6 Pt 1):C2062-71. doi: 10.1152/ajpcell.1996.271.6.C2062.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Anura
  • Calcium / physiology*
  • Models, Biological*
  • Models, Theoretical*
  • Muscle Contraction / physiology*
  • Muscle, Skeletal / physiology*

Substances

  • Calcium