Figure 4.

Characteristics of the current-voltage relationship in the presence or absence of extracellular Ca²⁺. A 10-s voltage ramp between −180 mV to +30 mV was applied every 30 s. The pipette solution contained: 5 mm ATP, 5 mm GTP, 75 mm SO₄²⁻, and 12.4 mm Cl⁻. The I-V curve was recorded in the standard bath (50 mm CaCl₂ and 5 mm MgCl₂) 10 min after breaking to the whole-cell configuration when a stable current amplitude was reached (50 mm Ca²⁺), and after 5 min of perfusion with the Ca²⁺-free bath (no Ca²⁺) (95 mm TEA-Cl, 5 mm LaCl₃). Results are shown for one representative experiment out of three. In all cases, the current amplitude was unchanged and the E_rev was not significantly modified.