FIGURE 5.
IM3 changes during 1-kHz sinusoidal fiber length oscillations in unmodified Ringer's solution (A) and in BDM (2 mM) Ringer (B). Upper traces, sarcomere length; middle traces, IM3 intensity (♦, expressed relatively to IM3 max); lower traces, forces (relative to control tetanic tension). Tetanic tension in presence of 2 mM BDM (B) was reduced to 0.65 Po. IM3 is shown over two periods of oscillation to display its waveform more clearly. The continuous lines through the IM3 data points show the best fit of a simulation of the IM3 signal obtained from the molecular structure of S1. The depth of the secondary minimum close to the point of minimum tension is increased in the presence of BDM, as is the separation between the double peaks in intensity that surround it.