Séminaires MSC
"Matière et Systèmes Complexes"


Lundi 18 juin 2007 à 11h30
Bâtiment Condorcet, 4ème étage, salle 454 A.

Lev Truskinovsky
(LMS, Ecole Polytechnique)

Why muscle response remains stable on a descending limb of the load-elongation curve?

We 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.