Axial and Radial Forces of Cross-Bridges Depend on Lattice Spacing
Figure 4
Overview and detail of the forces exerted by the 2sXB and 4sXB models in the post-power stroke state.
(A)–(D) show the post-power stroke forces exerted by the 4sXB and the 2sXB models as vector fields of reaction forces. The reaction force is that necessary to retain the cross-bridge head in a given location, thus the vectors for a compressed cross-bridge orient upwards and those for an extended cross-bridge orient downwards. Positions in which the cross-bridge is unlikely to generate force are omitted; these unlikely locations are determined by the sum of and the inverse of
. (A) and (B) show overviews of the forces exerted, respectively, by the 4sXB model and the 2sXB model over lattice spacings and axial offsets that vary as in Figure 2. The forces exerted by the two cross-bridges have radial components which frequently equal or exceed their axial components. A more detailed view of the region surrounding the rest position of the cross-bridges is shown in (C) and (D), where the large radial components of the cross-bridge forces, particularly for the 2sXB model, is especially evident.