The effect of high K+ (30 mM) – evoked Ca2+ transient and its impact on the FCCP-induced Ca2+ influx in WT and G93A transfected SH-SY5Y neuroblastoma cells. A) A representative figure showing effect of perturbing the mitochondrial Ca2+ uptake on the calcium transient evoked by 30 mM K+ depolarizing stimulus for 30s (red horizontal bar) and by 2 μM FCCP-evoked Ca2+ efflux (black horizontal bar). FCCP (2 μM) induced a fast, transient elevation in [Ca2+]i and a fast recovery to baseline after depolarization-induced stimulus in 7 SH-SY5Y cells transfected with WT. B) In G93A transfected SH-SY5Y cells, the FCCP-induced [Ca2+]i transient elevation after depolarization-induced stimulus was delayed 5–10s and there was a reduction in the magnitude of fluorescence intensity followed by complete recovery to baseline. C) A bar diagram to illustrate the reduction of the sustained Ca2+ response in G93A transfected SH-SY5Y neuroblastoma cells (F/F0 = 0.1497 ± 0.0362; N = 5, n = 20) compared to WT transfected SH-SY5Y cells (F/F0 = 0.2440 ± 0.0696; N = 3, n = 20). Values represent means ± SD, **p < 0.001, scale bar = 20 μm. N = Number of experiments; n = Number of cells.