Fig. 3.

Effect of β-arrestin 1 and -2 on the force–Ca²⁺ relationship. (A) Force–Ca²⁺ relationship in myofilaments harvested from left ventricles of WT mice at 1.9 μm and 2.3 μm. The change in calcium concentration producing one-half maximal tension (ΔpCa₅₀) at 1.9 μm vs. 2.3 μm was significantly different. *P < 0.05 for WT mice (n = 10 mice) at 1.9 μm vs. 2.3 μm by one-way ANOVA with Bonferroni’s multiple comparison test. (B) Force–Ca²⁺ relationship in β-arrestin 1 KO mice (n = 10 mice) at 1.9 μm and 2.3 μm. (C) Force–Ca²⁺ relationship in β-arrestin 2 KO mice (n = 11 mice) at 1.9 μm and 2.3 μm. (D) Average change in calcium concentration producing one-half maximal tension (ΔpCa₅₀) at 1.9 μm vs. 2.3 μm. *P < 0.05 vs. WT average ΔpCa₅₀ by one-way ANOVA with Bonferroni’s multiple comparison test. Error bars reflect SEM.