Figure 3. Feeding the HFD for 8 weeks induces an impaired contractility response to adrenergic stimulation in cardiomyocytes.

A and B, Western blots show the expression of cardiac β₁‐adrenergic receptor (β₁AR), β₂‐adrenergic receptor (β₂AR), G‐protein and G‐protein receptor kinase (GRK)2 in NC and HFD hearts. C and D, Western blots show the phosphorylation of β₂AR at both PKA and GRK sites in NC and HFD hearts. ^* P < 0.05 by Student's t test between paired groups. E, data show contractile function in response to β‐adrenergic stimulation (ISO, 100 nm) in adult cardiac myocytes isolated from NC and HFD mice. ^*** P < 0.001 by one‐way ANOVA followed by post hoc Tukey's test. F and G, data show PKA phosphorylation of PLB in response to β adrenergic stimulation (ISO, 100 nm) in the absence or presence of pertussis toxin (PTX, 1 μg ml⁻¹, 3 h) in adult cardiomyocytes isolated from NC and HFD mice (n = 3). ^* P < 0.05 by Student's t test between paired groups.