Fig. 1. Energized mitochondria increase the ability of InsP₃ to activate I_CRAC in weak intracellular Ca²⁺ buffer. (A1) Time course of I_CRAC to 5 µM InsP₃ in the absence (open circles) and presence (filled circles) of mitochondrial cocktail solution. (A2) Current–voltage relationships for the recordings shown in (A1), taken after 100 s. (B) Amplitude of I_CRAC (measured at –80 mV from the voltage ramps and normalized for cell capacitance) is plotted against InsP₃ concentration included in the recording pipette. Open and filled circles correspond to experiments in the absence and presence of the mitochondrial cocktail solution, respectively. (C) The percentage of responding cells is plotted against InsP₃ concentration. Note that, at 3 µM InsP₃, no cell responds in the absence of the mitochondrial cocktail whereas 50% do so when the cocktail is present.