Figure 5.

The enhancing action of aldosterone on IGF-I mediated signaling and biological actions is mediated in part by OPN binding to αVβ3 integrin. A and B, Quiescent VSMCs were incubated for 1 h with or without purified anti-αVβ3 IgG (1 μg/ml), and then aldosterone (10 nmol/liter) was added for 18 h followed by IGF-I (50 ng/ml) for 5 min and the levels of phosphorylated Akt, MAPK, and p70S6K were determined. The graph shows the ratio of phospho/total protein (mean ± sem, n = 3). IB, Immunoblot; Aldo, aldosterone. C, Cell proliferation. Cells were treated with or without purified anti-αVβ3 IgG (1 μg/ml), aldosterone (10 nmol/liter), and/or IGF-I (50 ng/ml) for 48 h, as indicated. Each value represents the mean ± sem of number of cells (×10⁴) of three replicate measurements from three independent experiments. D, Protein synthesis. VSMCs were incubated for 18 h with or without purified anti-αVβ3 IgG (1 μg/ml), aldosterone (10 nmol/liter), and/or IGF-I (50 ng/ml), as indicated. Each data point is the mean ± sd cpm of three independent experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.001.