Fig. 8.

The effect of LY294002, PP2 and MK-2206 on the Na,K-ATPase activity and ouabain-sensitive Rb uptake responses to insulin. Cells were exposed to PP2 (10 μM) for a total of 40 min, LY294002 (50 μM) for 30 min or MK-2206 (2.5 μM) for 20 min. Right side parts show ouabain-sensitive Rb uptake measured during the final 5 min when 100 nM insulin or vehicle (control) was added in Rb-containing Krebs solution. Half of the cells in each group also received ouabain (500 μM) and ouabain-sensitive Rb uptake was calculated as the difference between uptake in the presence and absence of ouabain. Left side parts show Na,K-ATPase activity (ouabain-sensitive ATP hydrolysis rate) measured in homogenates prepared from cells similarly exposed to the inhibitors and then to 100 nM insulin for 5 min. ATP hydrolysis in the treated and control groups was measured under identical conditions. Values shown are the mean ± SEM of results from five to six independent experiments. ***(p < 0001) indicates a significant difference from control. Levene’s test shows no heteroscedasticity in either set of data with P-values of 0.836 for Na,K-ATPase activity and 0.856 for the Rb uptake data sets, respectively.