Figure 5. Barium magnifies the effect of brief depolarizations on clamp current, surface pH and intracellular V_Ca.

For the first part of the records shown the preparation was bathed in normal snail Ringer but with only 1 mm Hepes buffer. After 3 depolarizations (to −10, −20 and −30 mV, respectively, the Ca²⁺ was replaced with Ba²⁺. Two more depolarizations were applied, both to −20 mV. Before the recordings shown, the preparation had been superfused with the Ba²⁺ solution for 30 min, followed by the Ca²⁺ saline for 10 min.