Figure 4.

Bcl-2 maintains Δψ in the presence of Ca²⁺ and tBuOOH by enhancing H⁺ efflux. Mitochondria (3 mg of protein per ml) isolated from livers were treated with 20 μM Ca²⁺ (A–C, solid arrows), 10 μM tBuOOH (D–F, solid arrow), 1 μM HCl (B and E, arrow a), or 50 μM KCl (C and F, arrow a). Then Δψ was assessed by Rh123 uptake (A and D), the external H⁺ concentration was determined with a pH electrode (B and E), and the external K⁺ concentration was measured with a K⁺ electrode (C and F). Data are representative of three experiments.