Figure 2.

The Ca²⁺-sensitizing effect of OM in permeabilized cardiomyocytes was quantified by pCa–force relationships ([Ca²⁺] between pCa 9 and pCa 4.75) in the absence and the presence of 0.1 μM or 1 μM OM. (A, B) Means of force amplitudes are expressed in absolute (kN·m⁻²) and normalized terms. (C) OM-evoked Ca²⁺ sensitization and the resultant leftward shifts in the pCa–force relations are illustrated by the means of their midpoints (pCa₅₀) in the absence and presence of 0.1 or 1 μM OM. (D) 0.1 or 1 μM OM decreased the co-operativity of Ca²⁺-regulated force production (n_Hill) in permeabilized cardiomyocytes (n = 8 cardiomyocytes from three different animals for each group). Each curve was generated with increasing concentrations of OM in the same cells. *P < 0.05, significantly different from control; repeated measures ANOVA with Dunnett’s two-tailed test.