Acute βAR stimulation induced-transactivation of PI3K signaling pathway is PKA-independent.

Adult male C57BL/6 mice were pretreated with vehicle (5% DMSO) or H-89 (20 mg/kg, i.p.) for 30 min before treatment with control (saline) or isoproterenol (ISO, 1.25 mg/kg, i.p.) for 30 min. (A) In vitro lipid kinase assay was performed as described. PIP, the phosphorylated end-product. The bar graph shows the densitometric scanning results of the measurement of PI3K activities in the control, ISO-treated and H-89 + ISO-treated mice (n = 4). (B, C) Representative Western blot analyses were performed on LV tissue lysates with antibodies against phospho-Akt (Thr308), phospho-Akt (Ser473), phospho-FOXO1 (Thr24), total Akt and total FOXO. The bar graphs show the densitometric scanning results. Data are normalized with individual total protein levels and represent means ± S.E. of percent change in protein phosphorylation relative to that of the control. *, p<0.05 versus the control.