Figure 4.

The effect of insulin is prevented by genistein and is not additive to the effect of orthovanadate. (A) Kidney proximal tubules were incubated for 30 min at 37°C in the absence (C) or presence of 10⁻⁸ M insulin (I) and/or 10⁻⁴ M genistein (G). Upper panel, immunoblot of proximal tubule extracts with McK1 antibody showing the effects of insulin and genistein on the amount of Na⁺, K⁺-ATPase α-subunit immunoprecipitated by the PY20 antibody. Lower panel, densitometric quantification of data shown in the upper panel. Results are expressed as percent of control optical density and are means ± SEM from seven independent experiments. (B) Proximal tubules were incubated for 30 min at 37°C in the absence (C) or presence of 10⁻⁸ M insulin (I) and/or 10⁻³ M orthovanadate (V). Upper panel, immunoblot of proximal tubule extracts with McK1 antibody showing the effects of insulin and orthovanadate on the amount of Na⁺, K⁺-ATPase α-subunit immunoprecipitated with the PY20 antibody. Lower panel, densitometric quantification of data shown in the upper panel. Results are expressed as percent of control optical density and are means ± SEM from six independent experiments (*, p < 0.05 vs. control).