Figure 5. Effects of Ba²⁺ on resting membrane potential of BPA cells.

A, representative tracings of single maxi-K⁺ channel current in a cell-attached patch in the absence or the presence of Ba²⁺ (100 µm or 1 mm) in the bath solution. Voltage (-V_p) was +83 mV. The patch pipette was filled with the KCl-rich (150 mm K⁺) solution (solution E) and the bath contained the standard NaCl-rich solution (solution B). B, I-V relations of maxi-K⁺ channel obtained from the patch shown in A before (○), during (100 µm (•) or 1 mm (▪) addition of Ba²⁺ to the bathing solution and after washout of Ba²⁺ (□). C, Ba²⁺ (100 µm or 1 mm)-induced changes in V_m indicated by the reversal of single maxi-K⁺ channel current in cell-attached patches. Application of TEA (10 mm) to the bathing solution did not shift the reversal potential.