Figure 4.

Inhibition of Na⁺ feedback by intracellular amiloride. (A) Concentration-dependency of the effect of intracellular amiloride when included in 20 mM Na⁺ solution. (B) The effect of the inclusion of 0.2 μM activated recombinant α-subunit of G_o (act G_o) and amiloride (10 and 30 μM) in the zero Na⁺ pipette solution. AS and inact G_o denote controls in which activation solution or inactive Gα_o, respectively, were added to the pipette solution. (C) The effect of the inclusion of anti-Nedd4 antibody (A-Nd4; 1 μg purified IgG/ml), GST-WW fusion protein (G-W; 0.3 mg/ml), GST-wild type-ubiquitin (wt; 0.3 mg/ml) or GST-dominant negative-ubiquitin (K48R) fusion protein (dn; 0.3 mg/ml) in the 20 mM Na⁺ pipette solution. In A the broken line indicates the mean rate of pH_i recovery observed with zero Na⁺ pipette solution.