Fig. 5. Recordings showing the effect on V_bl of addition of 6 mmol l^–1 Ba²⁺ before and after exposure to (A) 10^–4 mol l^–1 ouabain, (B) K⁺-free saline and (C) Cl^–-free saline. The tubules were exposed to the different conditions for the periods indicated by the horizontal bars.