Acute βAR stimulation in vivo increases cardiac PI3K activity and phophorylation of Akt and ERK1/2.

<p>Adult male C57BL/6 mice were treated with vehicle control or isoproterenol (ISO, 1.25 mg/kg, i.p.) for 30 min. (A) Left ventricular tissue lysates were IP with an anti-pY antibody and subjected to <i>in vitro</i> lipid kinase assay. PIP, the phosphorylated end-product. The bar graph shows the densitometric scanning results of the measurement of PI3K activities in the control (n = 6) and ISO-treated (n = 6) mice. (B, C) Representative Western blot analyses were performed on LV tissue lysates with antibodies against phospho-Akt (Thr308), phospho-Akt (Ser473), total Akt, phospho-ERK1/2 (Thr202/Tyr204) and total ERK1/2. The bar graphs show the densitometric scanning results from two individual experiments (n = 6). In another series of experiments, mice were pretreated with vehicle (5% DMSO) or LY294002 (LY, 1.4 mg/kg, i.p.) for 30 min before the ISO treatment. In vitro lipid kinase assay (D) and Western blot analyses (E) were performed as described above. The bar graph shows the densitometric scanning results in the control (n = 6), ISO (n = 6), and LY/ISO (n = 6) groups. In all Western blotting experiments, data were normalized with individual total protein levels. *, p<0.05 versus vehicle control.