Figure 5: Example elastic and viscous moduli from mouse cardiac muscle strips. (a, b) The elastic and viscous moduli recorded at frequencies ranging 0.125–250 Hz for wild-type mouse cardiac muscle expressing -MyHC at maximum calcium activation and 37°C. The frequency characteristics of the dips and shoulders are reflective of the underlying enzymatic activity and shift to lower frequencies as MgATP is reduced from 5 to 1 mM. (c, d) The elastic and viscous moduli recorded for PTU-fed mouse cardiac muscle expressing -MyHC. Frequency characteristics appear at lower frequencies compared to -MyHC. Again, characteristics shift to lower frequencies as MgATP is reduced.