Abstract
The same prototypal model used in a previous paper to illustrate proper construction of a muscle model is modified here with the much more realistic choice eΔp = 108 rather than eΔp = 100, where eΔp is the ratio of physiological ATP activity to equilibrium ATP activity. For steady isotonic contractions, the range 1 ≤ eΔ ≤ 104 can be approximated quite well by use of linear terms only in expansions of F̄ (force) and J̄ (ATP flux) in powers of eΔ - 1 and v (velocity). This will presumably also be true in most cases of much more complicated models. However, this region is of theoretical interest only (irreversible thermodynamics, etc.) because F̄ and J̄ are very small. In addition, numerical calculations of F̄ and J̄ were made in the region 104 ≤ eΔ ≤ 108. The optimal efficiency η* is larger under physiological conditions (about 1%) than at equilibrium by a factor of 2.1 × 104. The rate of entropy production is discussed in this connection.
Keywords: sliding filament model, isotonic contractions, efficiency, irreversible thermodynamics
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Selected References
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