Figure 6.

Caffeine stimulates [Ca²⁺]i release with slower kinetics and weaker transient than the FCCP-evoked [Ca²⁺]i signals in SH-SY5Y neuroblastoma cells, particularly in WT transfected cells compared to G93A transfected cells. A) The kinetic profile of caffeine and FCCP-evoked [Ca²⁺]i release in the WT transfected SH-SY5Y neuroblastoma cells. The trace is representative of 5 cells in focus stimulated with 5mM caffeine and 2µM FCCP (normalized data, 5 point smoothing). B) The corresponding kinetic profile of the caffeine and FCCP-evoked [Ca²⁺]i release in the G93A transfected SH-SY5Y cells. The trace is representative of 5 cells in focus stimulated with 5mM caffeine and 2µM FCCP (normalized data, 5 point smoothing). The ER and mitochondrial Ca²⁺ release from these two compartments were measured simultaneously. The horizontal black bars indicate the duration of stimulation by caffeine and with FCCP plus caffeine. Fura-2 AM signals are represented as F/F0. C) A bar diagram of caffeine and FCCP plus caffeine-induced Ca²⁺ release in the WT and G93A transfected SH-SY5Y neuroblastoma cells (N=3, n=14). Gray bars represent caffeine plus FCCP-induced Ca²⁺ release in WT (F/F0 = 0.1883 ± 0.0584) and G93A (F/F0 = 0.1154 ± 0.0246) transfected SH-SY5Y cells. Striped bars represent caffeine-induced Ca²⁺ release in WT (F/F0 = 0.0471 ± 0.0190) and G93A (F/F0 = 0.0353 ± 0.0120) transfected cells. Values represent means ± SD, *p<0.01, **p<0.001. N= Number of experiments; n= Number of cells.