(430k) Transient Dynamics of a Four State Actomyosin Model of Muscle Contraction

A recent model of muscle action(Long and Phoonsiri, Chem. Eng. Comm., 193:pp306-337, 2006)has been used to compute the steady state response of mechanical and chemical variables in muscle contraction. The merits of a model of this action, however, depend on both its steady state and transient responses. This model depends on a posited high strain and low strain state for the actomyosin*ADP complex (designated AMADP). Combining these two strain states with a simple averaging rule and mass action kinetic models for the biochemical cycle allows for computation of both steady state and transient responses. The transient responses are considered here. This model links the nanoscale to the macro scale by simple addition of action combined with non-dimensional presentation of the results. Comparison of nano-scale can thus be made with well known macroscale mechanical test results. Because a complete set of kinetic data was not found for the required chemical species, a set of hybrid data was assembled from data for different species (mostly rabbit, but also some frog as well as barnacle data). In spite of this disparate data set, the results are very encouraging. In addition, some further modeling of compliance effects is necessary, but very good computations can be obtained without including these effects.