Mitochondrial sequestration of Ca2+ released from caffeine-sensitive stores. Cells were coloaded with rhod-2 and Calcium Green and examined in perforated patch as in Fig. Fig.4.4. (A) Cam and Cac responses from another cell subjected to sequential depolarizations of 0.5 s applied before (circle), and of 1.0 or 1.5 s (box) applied after perfusion with 10 mM caffeine and 10 μM BHQ. (B) Averaged responses from three cells treated exactly as above. The enlarged, closed symbols mark the observed Cam and Cac values at the termination of stimulus. The intermediate response to the first depolarization applied after treatment is not shown, to avoid excessive overlap of records.