Figure 4

The twitch DT at various sarcomere lengths is shown in A for contractions obtained prior to (P_t) and after (P_t*) a 1.5 s tetanic contraction at 75 Hz when bath solution temperature was 22°C. In this case, like for staircase, there was enhancement of DT at short sarcomere lengths, but unlike the case for staircase, there was a clear force depression at long sarcomere lengths. As seen in B, the P_t*/P_t decreases with increases in sarcomere length. The results of 4 muscles are shown. Regression analysis gave r² = 0.80 and P_t*/P_t = -0.50·SL + 2.45 (where SL is sarcomere length).