FIGURE 1.

(A) A microelectrode (ME) consisting of pH- and Ca²⁺-sensitive barrels was moved at 2 μm/s perpendicular to the lipid plane formed by the bilayer itself, the torus, and the lipid on the Teflon support. (B) Representative experimental records induced by 2.5 μM A23187 in the presence of a 2:0.2 mM transmembrane [Ca²⁺] gradient (bulk solution: 1 mM Tris, 1 mM Mes, 100 mM choline chloride, pH 7). After touching the membrane, the electrode was withdrawn to a distance of 20 μm. Switching the transmembrane potential from 0 to +150 and then −150 mV revealed no effect, suggesting that the Ca²⁺/2H⁺ exchange is electroneutral.