Representative stretch activation traces from WT and SA myocardial preparations. (A and B) Representative stretch activation responses to a rapid 2% increase in ML in WT (A) and SA (B) myocardial preparations measured at pCa 6.1 to illustrate the dose-dependent effect of OM on force generation. WT myocardial preparations showed a dose-dependent OM-mediated increase in force development, whereas increase in force development was observed only following 1.0 µM OM incubation in the SA myocardial preparations.