Fig. 5

Tacrolimus causes ER Ca²⁺ depletion and ER Ca²⁺ leak. Endoplasmic reticulum (ER) Ca²⁺ stores (maximal peak amplitudes of caffeine-induced Ca²⁺ release, (a) and ER Ca²⁺ leak (b) were assessed following 24 h incubation with vehicle or 5 nM tacrolimus. c Direct evaluation of ER Ca²⁺ (representative curves, the arrow indicates thapsigargin, 1 μm) using the ER-targeted probe D1ER (left). The slope of the FRET ratio decrease after thapsigargin addition represents a bona fide measurement of the rate of Ca²⁺ leak (right), consistent with the results depicted in panel b. Data are presented as mean ± S.E.M. of at least 5 experiments performed in triplicate; *:p < 0.05 vs vehicle