FIGURE 2.

Mitochondrial Ca²⁺ transport in permeabilized Drosophila S₂R⁺ cells. Digitonin-permeabilized S₂R⁺ cells were incubated in 130 mm KCl, 10 mm MOPS-Tris, 5 mm P_i-Tris, 5 mm succinate-Tris, 10 μm EGTA, 2 μm rotenone, and 0.5 μm Calcium Green 5N, pH 7.4. A, in trace b only, the incubation medium was supplemented with 0.2 μm RR; where indicated, 25 μm Ca²⁺ with no further additions (trace a) or followed by 0.2 μm RR and by 0.1 mm (trace c), 1 mm (trace d), or 10 mm NaCl (trace e). B, rate of Na⁺-induced Ca²⁺ release obtained in protocols such as those depicted in A as a function of the added Na⁺ concentration; values were normalized to the rate observed after the addition of 10 mm NaCl (taken as maximal), and error bars report the S.D. of triplicate experiments. C, in trace e only, the medium was supplemented with 1 μg/ml cyclosporin A; where indicated, 25 μm Ca²⁺ was added followed by the addition of 0.2 μm RR and/or 0.5 μm FCCP where indicated by arrows as follows: no addition after the Ca²⁺ pulse (a), RR only (b), FCCP only (c), and RR and FCCP (d and e). D, where indicated, 25 μm Ca²⁺ pulse, 0.2 μm RR, 0.5 mm (b), 1 mm (c), or 2 mm (d) tetracaine and 0.5 μm FCCP. Trace a was obtained after the addition of RR and FCCP without tetracaine.