Cardiac mechanoenergetics replicated by cross-bridge model

The aim of this work is to reproduce the experimentally measured linear dep endence of cardiac muscle oxygen consumption on stress-strain area using a model, composed of a three-state Huxley-type model for cross-bridge interac tion and a phenomenological model of Ca2+-induced activation. By selecting particular cross-bridge cycling rate constants and modifying the cross-brid ge activation model, we replicated the linear dependence between oxygen con sumption and stress-strain area together with other important mechanical pr operties of cardiac muscle such as developed stress dependence on the sarco mere length and force-velocity relationship. The model predicts that (1) th e amount of the "passenger" cross bridges, i.e., cross bridges that detach without hydrolyzing ATP molecule, is relatively small and (2) ATP consumpti on rate profile within a beat and the amount of the passenger crossbridges depend on the contraction protocol. (C) 2000 Biomedical Engineering Society . [S0090-6964(00)00206-X].