Figure 4

Suppression of STIM1 results in reduced Ca²⁺ influx in response to histamine but not bradykinin. (a & b) Representative traces illustrating bradykinin induced [Ca²⁺]_i changes in HASMs treated with 20 nM STIM1 siRNA (a) and 20 nM STIM2 siRNA (b) compared with control. (c) Summary of data represented in (a & b) showing average changes in fluorescence after 2 mM Ca²⁺ re-addition. (d & e) Representative traces illustrating histamine induced changes in [Ca²⁺]_i in HASMs treated with 20 nM STIM1 siRNA (d) and 20 nM STIM2 siRNA (e) compared with control. (f) Summarized data from (d and e) showing average fluorescence changes after 2 mM Ca²⁺ re-addition. Bradykinin (1 μM) or Histamine (100 μM) was added to cells in low extracellular Ca²⁺ (0.1 mM) followed by the restoration of 2 mM Ca²⁺ as indicated. The summarized data (c & f) are shown with subtraction of agonist independent (basal) calcium influx. Results are expressed as % changes ± sem compared to control and represent averaged data from at least 3 experiments. Data are indicated as statistically significant with *P < 0.05 and **P < 0.01.