Figure 8.

Induction of TRPM3 in differentiated human neuroblastoma IMR‐32 cells and effects of Dic. Non‐neuronal IMR‐32 cells were differentiated to nIMR‐32 cells with BrdU treatment (see Materials and Methods). (A) To confirm quantitative induction of TRPM3, TRPM3 mRNA transcripts were compared between IMR‐32 and nIMR‐32 cells (six independent experiments). ** versus IMR‐32. (B and C) The Ca²⁺ response (ΔCa²⁺ _i) to 30 μmol/L PregS was shown in representative three IMR‐32 and nIMR‐32 cells, and the pooled data were summarized as a bar graph (C, four independent experiments for IMR‐32 and nIMR‐32 cells, respectively). ** versus IMR‐32. (D and E) Cumulative application of PregS between 1 and 300 μmol/L to nIMR‐32 cells. Typical traces (D, one responsive and another nonresponsive cell to PregS) and summarized data of responsive cells (E, four independent experiments) were shown. (F) Application of 3–100 μmol/L Dic to nIMR‐32 cells significantly inhibited PregS‐induced Ca²⁺ response. Bars represent the mean ± SEM (five to eight independent experiments). Data were fitted to a sigmoid curve to determine the apparent IC ₅₀ of Dic against PregS‐induced Ca²⁺ responses. TRPM, transient receptor potential melastatin; IMR‐32, human neuroblastoma IMR‐32; Dic, diclofenac; nIMR‐32, neuronal IMR‐32; BrdU, 5‐bromo‐2′‐deoxyuridine; PregS, pregnenolone sulfate.