Figure 8.

AZC does not acutely affect cytosolic Ca²⁺ but pretreatment with AZC reduces the Ca²⁺ amount detected in the cytosol after ER Ca²⁺ store release evoked by thapsigargin (TG). Results are shown as mean ± SEM (indicated by the dotted lines) of three independent experiments each performed in duplicate. (A) Cells were loaded with 1.8 μM Fura-2 AM for 30 min, followed by 30 min of deesterification. Fura-2 AM fluorescence was monitored using a FlexStation 3 microplate reader. Extracellular Ca²⁺ was chelated with 3 mM EGTA and 120 s later AZC or 1 μM TG (as a positive control) was added as indicated. (B) Cells were pretreated for 6 h with 5 mM or 10 mM AZC. During the last hour of treatment, cells were loaded with 1.8 μM Fura-2 AM for 30 min, followed by 30 min of deesterification. Extracellular Ca²⁺ was chelated with 3 mM EGTA and 120 s later 1 μM TG or Krebs solution (vehicle) was added as indicated. (C) Quantification of the area under the curve of the Ca²⁺ traces in (B) * p < 0.05. (D) Time constant τ for the decline phase of the Ca²⁺ traces in (B) *** p < 0.001.