Representative stretch activation traces from PKA-treated WT and SA myocardial preparations. (A and B) Representative stretch activation responses to a rapid 2% increase in ML in PKA-treated WT (A) and PKA-treated SA (B) myocardial preparations measured at pCa 6.0 to illustrate the effect of OM on force generation. Incubation with 1.0 µM OM significantly increased force development in the PKA-treated WT and SA myocardial preparations.