Fig. 2.
Effect of β-arrestin 1 and -2 on the cardiac response to volume loading. (A and B) Representative serial PV loops from a β-arrestin 1 KO mouse (A) and a β-arrestin 2 KO (B) mouse during volume infusion protocol. SV in both basal loops (SV) and in loops recorded after completion of volume loading (SV′) is denoted by the gray arrows. (C) Effect of volume infusion on absolute change in SV from baseline in β-arrestin 1 KO and β-arrestin 2 KO mice compared with WT mice. P values for the interaction between LVEDP and change in SV for data comparison were obtained by two-way repeated-measures ANOVA. *P < 0.005 for comparison between genotypes at a given LVEDP value using Bonferroni’s multiple comparison test. (D) Effect of balloon stretch on developed force in an ex vivo hanging heart preparation. Shown is the average percentage increase in LV dP/dtmax from baseline shown for WT, β-arrestin 1 KO, and β-arrestin 2 KO mice. P values for the interaction between heart beat number and genotype for data comparison were obtained by two-way repeated-measures ANOVA. *P < 0.05 for comparison between genotypes at a given heart rate using Bonferroni’s multiple comparison test. Error bars reflect SEM.