FIGURE 4.

A, dissipation of pH gradient on membranes of pyranine-loaded liposomes by SkQR1, SkQR4, and FCCP. Inner liposome pH was estimated from the ratio (I₄₅₅/I₄₁₀) of pyranine fluorescence intensities measured at 505 nm upon excitation at 455 and 410 nm, respectively. Nigericin (1 μm) was added at 550 s to equilibrate the pH. The control curve is with FCCP but without valinomycin. Concentrations were as follows: SkQR1 (100 nm), SkQR4 (100 nm), FCCP (100 nm), valinomycin (10 nm), and lipid (75 μm). B, dose dependence of the effect of SkQR1 and FCCP. The control curve corresponded to 10 nm valinomycin without protonophores.