Figure 6.

Action of Cd²⁺ on the transmembrane potential of spring lamprey liver mitochondria in the absence or presence of cyclosporine A and/or dithiothreitol. The lamprey liver mitochondrial membrane potential was estimated with the help of fluorescent lipophilic cation, safranine O, by measuring changes in intensity of its fluorescence (in arbitrary units) on a Shimadzu RF-1501 spectrofluorometer at the excitation wavelength of 485 nm and emission wavelength of 590 nm. Mitochondria (0.5 mg/mL of protein) were added into a medium containing 250 mM sucrose, 3 mM MgCl₂, 3 mM KH₂PO₄, 3 mM Tris-HCl (pH 7.3), and 3 μg/mL of oligomycin and 4.5 μM of safranine O, as well as respiratory substrates: 5 mM of glutamate and 5 mM of malate, or 5 mM of succinate plus 5 μM of rotenone. Cd²⁺ (5 μM), DTT (1 mM), and FCCP (1 μM) were added where indicated by arrows. [CsA], if added, was 1 μM. Typical traces for 3–5 independent experiments are shown.