Benzbromarone (Benzb) attenuates an increase in intracellular calcium induced by histamine or bradykinin in cultured human airway smooth muscle cells. (A) Representative fura-2 calcium tracings in the presence of 2 mM extracellular calcium. Human airway smooth muscle cells were pretreated with either vehicle (0.1% dimethyl sulfoxide [DMSO]) or Benzb (10, 50, and 100 μM), and then 10 μM histamine was pipetted into the wells of the plate. An increase in intracellular calcium was attenuated in a concentration-dependent manner by pretreatment with Benzb. (B, C) Average peak fluorescence in 2 mM extracellular calcium. Cells were pretreated with either vehicle (0.1% DMSO; n = 12) or Benzb (10, 50, and 100 μM) and then 10 μM histamine (B) (n = 9) or bradykinin (C) (n = 6). Pretreatment with Benzb (10, 50, and 100 μM) showed an attenuation of increases in intracellular calcium when compared with vehicle control (***P < 0.001). Attenuation was concentration dependent (#P < 0.001 compared with 10 μM, $P < 0.01 compared with 50 μM). (D) Representative tracing (as in fig. 7A) of intracellular calcium concentrations in the absence of extracellular calcium. Increases in intracellular calcium were attenuated by pretreatment with increasing concentrations of Benzb. (E, F) Average peak fluorescence (as in fig. 7, B and C) of intracellular calcium induced by histamine or bradykinin in the absence of extracellular calcium. Pretreatment with Benzb (50 and 100 μM) showed an attenuation of increases in intracellular calcium when compared with vehicle control (***P < 0.001; vehicle and 50 μM Benzb: n = 10 and 10 and 100 μM Benzb: n = 7).