Figure 9. SERCA pump block is sufficient to activate I_CRAC even in high intracellular Ca²⁺.

A, InsP₃ and thapsigargin can activate I_CRAC in weak buffer even in the presence of high intracellular Ca²⁺ (100 μm total CaCl₂ in the pipette solution, free Ca²⁺ concentration estimated to be in the micromolar range). Thapsigargin alone was also able to evoke I_CRAC under these conditions, but after a delay and at a slower rate. B, aggregate data are summarised.