FIGURE 8.

G_iCT inhibits β₂AR/G_i coupling for myocyte contraction rate response upon agonist stimulation. A, the maximal responses in contraction rate induced by the β₂AR were enhanced by expression of G_iCT along with the wild type β₂AR in β₁β₂AR-KO cardiac myocytes. B–D, the β₁β₂AR-KO cardiac myocytes expressing the β₂AR, PKAmut β₂AR, or GRKmut β₂AR were stimulated with 10 μm Iso in the presence or absence of G_iCT. The response in myocyte contraction rate was measured. E and F, the base-line levels of contraction rates and the maximal increases in contraction rates after stimulation in the presence or absence of G_iCT were plotted. **, p < 0.01; ***, p < 0.001 when compared with the wild type receptor by two-way ANOVA. *, p < 0.05 when compared with the group without G_iCT in Student's t test.