Fig. 2.

OAG-induced Ca²⁺ efflux from rat brain mitochondria is not mediated by known Ca²⁺ uptake and release pathways. (A): Mitochondria are loaded by exogenously added Ca²⁺ (each pulse is 400 nmol CaCl₂) and the following compounds are administered: trace a, OAG (100 μM) at 500 s; trace b, 165 nM Ru360 at 300 s, 1 μM antimycin A₃ plus 2 μM oligomycin at 500 s; trace c, 165 nM Ru360 at 300 s, 0.5 μM FCCP at 500 s; trace d, 165 nM Ru360 at 300 s, 100 μM OAG at 500 s; trace e, 165 nM Ru360 at 300 s, 20 μM CGP-37157 at 400 s, 100 μM OAG at 500 s; traces d and e are superimposed. “Eff.”: effectors. (B): 1 mM LaCl₃ abolishes OAG-induced Ca²⁺ efflux, without affecting the reverse function of the uniporter: mitochondria are treated with 400 nmol CaCl₂ at 350 and 600 s and 1 mM LaCl₃ in between (500 s). Subsequently 1 μM antimycin A₃ plus 2 μM oligomycin are administered at 800 s (trace a) or 100 μM OAG at 800 s (trace b). In trace a 0.5 μM FCCP was also added at 1100 s. In both traces, alamethicin (40 μg/ml) is added at 1200 s. (C): In trace a, rat brain mitochondria are not preloaded with Ca²⁺, and Ru360 (165 nM) is added at 300 s; subsequently, 800 nmol of CaCl₂ is added at 350 s, followed by two pulses of OAG (100 μM each) at 400 and 500 s. In trace b, mitochondria are preloaded with two pulses of exogenously added CaCl₂ (100 and 200 s, 400 nmol each); 165 nM Ru360 is added at 300 s, followed by an additional pulse of 400 nmol CaCl₂ at 350 s. Subsequently OAG (two pulses of 100 μM each) are added at 400 and 500 s. In both traces, alamethicin (40 μg/mL) is added at 1200 s.