FIGURE 1.

NAADP mobilizes Ca²⁺ from acidic Ca²⁺ stores in mouse primary β cells. A, clusters of β cells were superfused with 3 mm glucose and stimulated by NAADP-AM, 10 nm (red line), 60 nm (black line), and 10 μm (blue line), and glucose (10 mm) as indicated. B, clusters of β cells were pre-treated with 1 μm thapsigargin (TG) for 1 h. They were then stimulated by NAADP-AM (60 nm) in the absence of extracellular Ca²⁺ and in the presence of a nonstimulatory glucose concentration (3 mm). C, NAADP-AM-induced [Ca²⁺]_i response observed in B is prevented by bafilomycin (Baf, 3 μm) treatment. D, pretreatment of β cells with Ned-19 (100 μm) blocks the NAADP-AM-induced [Ca²⁺]_i rise observed in B. E and F, quantification of the results from A to D. Traces are representative of results obtained in 8 (A), 7 (B), 6 (C), and 6 (D) clusters of islet β cells.