FIGURE 1.

Effects of NAADP and BZ194 on intracellular Ca²⁺ release. a–d, cardiac myocytes were loaded with Fura-2/AM and subjected to combined Ca²⁺ imaging and intracellular infusion via a patch clamp pipette. a, change in [Ca²⁺]_i is shown in pseudo-color images at different time points before and after establishing the whole-cell configuration. The position of the patch pipette can be seen in the bright field image (scale bar, 30 μm). Infusion of nominal Ca²⁺-free intracellular buffer did not change [Ca²⁺]_i. In contrast, infusion of 37.5 nm NAADP resulted in release of Ca²⁺. Incubation with 0.5 μm bafilomycin A1 or co-infusion with 10 μm ruthenium red or 10 μm BZ194 blocked the NAADP-induced Ca²⁺ release. IC, nominal Ca²⁺-free intracellular buffer. b–d, change in [Ca²⁺]_i after establishing the whole-cell configuration is summarized for the different conditions as mean ratio 340:380 ± S.E., n = 3–41 as indicated in the bars. Asterisks indicate statistical significance for NAADP compared with buffer control (p < 0.05). Number signs indicate statistical significance for NAADP plus bafilomycin A1, plus ruthenium red, or plus BZ194 compared with NAADP alone (p < 0.05). n.s. means not significant. Statistical significance versus control or NAADP alone was calculated by Mann-Whitney rank sum test. d, 0.1% (v/v) DMSO was used as control.