Fig. 6. Neither Ins(1,4,5)P₃ (IP₃)- nor I_Ca-induced [Ca²⁺]_c increases altered the _m of the entire-cell mitochondrial complement when measured with TMRE in `quench' mode. _m depolarization was not seen during increases of [Ca²⁺]_c induced by either Ins(1,4,5)P₃ (released by localized photolysis of caged Ins(1,4,5)P₃, at , A), following a single plasmalemmal depolarization (+10 mV for 500 ms, B) or following a train of plasmalemmal depolarizations (+10 mV for 250 ms, 2 Hz, 5 seconds, C) in myocytes co-loaded with Fluo-4 (10 µM) and TMRE (150 nM, see text). By contrast, the mitochondrial inhibitors CCCP plus oligomycin (1 and 6 µM, respectively, D) significantly increased TMRE fluorescence when compared with untreated controls (E); ^**P<0.01; n.s. (not significant) P>0.05.