FIGURE 4.

NFT does not cause Ca²⁺ leakage from ER. Changes in the Ca²⁺ concentration of the ER were monitored with the Ca²⁺ sensor D1ER expressed in HEK cells. Cells were exposed to various concentrations of (a) NFT and (b) ES24 for 15 min to explore possible changes in ER Ca²⁺ when SERCA pumps were active. Graphs depict ER Ca²⁺ expressed as normalized D1ER ratios. Subsequently, SERCA pumps were blocked with 1 µM thapsigargin (TG) to unmask the Ca²⁺ leakage from ER. (c) Comparison of the ER Ca²⁺ depletion between DMSO controls and NFT‐ or ES24‐treated cells. ER Ca²⁺ depletion was measured 1 min before TG‐application. The dotted line illustrates the maximal Ca²⁺ depletion at 30 min. N: 17–34 cells per experimental setting. n.s., non‐significant; ***, p < .001 [Colour figure can be viewed at wileyonlinelibrary.com]