Fig. 5. Dynamic adhesive strength of primary myotubes. C57 and SG^–/– myotubes have similar dynamic adhesive strength. (A) Forced peeling was done with a large-bore micropipette. The shear stress, _cell, of the aspirating fluid imposed a tension, T_peel, which peeled the cell from the substrate at a velocity V_peel. The flow rate, Q, was held constant by a syringe pump, but T_peel increased linearly with the length of cell inside the micropipette, L_asp. The fluid velocity u_z within the pipette is parabolic in profile as sketched. (B) A typical peeling run exhibits dips in the velocity as a function of tension. These dips correspond to physical focal adhesions (PFA, empty squares) along the length of the cell. The velocity envelope that defines `peeling' (filled squares) can be compared between cell types. (C) A comparison of peeling data for normal (C57) and SG^–/– cells revealed no significant difference in peeling dynamics. The R² for the C57 and SG^–/– fits are 0.71 and 0.84, respectively.