FIGURE 6.

Increased calcium retention by valinomycin is not blocked by PKC inhibition or associated with increased H₂O₂ generation. A, shown is CRC of brain mitochondria during a continuous calcium infusion as described in Fig. 1. Mitochondria with 150 pm valinomycin were pretreated with the PKC inhibitor Ro318220 (100 nm), the free radical scavenger MPG (300 μm), or 2000 units/ml of the antioxidant catalase. MPG reduced CRC with and without valinomycin, indicating a nonspecific negative effect. The asterisks indicate significant difference between groups. B, H₂O₂-dependent oxidation of Amplex Red to the fluorescent product resorufin was followed during calcium infusion for control (Ctrl) and valinomycin-treated (Val, 150 pm) brain mitochondria. Inserted numbers display mean H₂O₂ generation rate in pmol/min/mg. The asterisk indicates significant difference compared with control. a.u., arbitrary units.