Impact of OM on the dynamic XB parameters in WT and SA myocardial preparations. The effects of OM on dynamic XB parameters derived from stretch activation responses in pre-OM, 0.5 µM OM–, and 1.0 µM–treated WT and SA myocardial preparations are shown at pCa 6.1. (A and B)k_rel before and following OM incubations in WT (A) and SA (B) myocardial preparations. (C and D)k_df before and following OM incubations in WT (C) and SA (D) myocardial preparations. (E and F) P1 before and following OM incubations in WT (E) and SA (F) myocardial preparations. (G and H) P_df before and following OM incubations in WT (G) and SA (H) myocardial preparations. Data from multiple preparations from each heart were averaged, and 12–15 myocardial preparations from four or five different hearts were used per group. Values are expressed as mean ± SEM. *, Significantly different compared with the corresponding pre-OM group; P < 0.05. &, Significantly different compared with the corresponding WT group.