"Matière et Systèmes Complexes"
18 juin 2007 à 11h30
Bâtiment Condorcet, 4ème
étage, salle 454 A.
(LMS, Ecole Polytechnique)
Why muscle response remains stable on a descending limb of the load-elongation curve?
present a new model of a tetanized skeletal muscle, where myofibrils
are represented by a series connection of sarcomeres which are
coupled trough an elastic environment. Sarcomeres are
characterized by a non-monotone force-length relation and, as a result,
the mechanical system exhibits rugged energy landscape with
multiple metastable inhomogeneous configurations. The model shows
nontrivial behavior on the descending limb of the load-elongation and
predicts in its vicinity a fine mixture of short and long sarcomeres.
The variation of the degree of non-uniformity with elongation follows a
complete devil's staircase. The model is compatible with an extended
domain of hysteretic behavior in the area adjacent to the descending
limb, whichis confirmed by experiments.