Fig. 6. C₂ ceramide causes a time-dependent elevation in the [Ca²⁺]_c. HeLa cells were loaded with the Ca²⁺ indicator Fura-2/AM and [Ca²⁺]_c changes were measured as detailed in Materials and methods. The coverslips with the cells were maintained in 1 mM Ca²⁺/KRB (A and B) or in Ca²⁺-free 0.5 mM EGTA/KRB (C and D). Where indicated, the cells were challenged with 10 µM ceramide (+ Cer) (A and C) or 10 µM di-hydroceramide (DH-Cer) (B and D). The traces show the calibrated [Ca²⁺]_c values {Δ[Ca²⁺] are 212 ± 35 nM (A), 20 ± 15 nM (B), 40 ± 12 nM (C), 6 ± 4 nM (D)}. The experiment shown is representative of at least five similar trials. Ionomycin (Iono).