Fig. 5.

Effect of NHE-1 inhibition on stimulation of Na-K-ATPase-mediated ⁸⁶Rb uptake in kidney proximal tubular cells by ouabain. Intact cells were treated for 15 min with vehicle, 10 nM (OK cells, A) or 10 pM (HK cells, B–D) ouabain in the presence or absence of NHE-1 inhibitor EIPA (5 μM). Na-K-ATPase-mediated ⁸⁶Rb uptake was measured as described in experimental procedures. Each bar represents means ± SE from 6 independent experiments performed in triplicate. Of note, all ⁸⁶Rb experiments were performed in the presence of a sodium ionophore (monensin; 5 μM) such that the uptake was measured at V_max for sodium. *P < 0.05 by 1-way ANOVA followed by Bonferroni analysis (GraphPad Prizm).