Figure 4.

Capacitative Ca²⁺ influx in control, Bcl-2–transfected, and Ca²⁺-deprived cells. A, Representitive trace. B, Average [Ca²⁺] peak. Parallel batches of HeLa cells were either cotransfected with cytAEQ and Bcl-2 (Bcl-2), or transfected with cytAEQ alone (control and Ca²⁺-deprived). In the Ca²⁺-deprived cells, the cells were maintained in the 18 h preceding the experiment in KRB containing a lower (0.1 mM) CaCl₂ concentration (KRB/lowCa²⁺). After transferring the coverslip with the cells to the luminometer chamber, the cells, perfused with KRB/EGTA, were challenged with 10 μM tBuBHQ (a specific blocker of the Ca²⁺ ATPase present in the ER and Golgi apparatus) added to the same medium. After 2 min, capacitative Ca²⁺ entry was initiated by changing the medium to KRB/Ca²⁺ (CaCl₂). All other conditions as in Fig. 1.