Figure 3.
5-HT2B mediates 5-HT-induced [Ca2+]i increase in HEK293T cells through the Gq pathway. HEK293T cells were transfected with p-IRES-GFP-5-HT2B or pIRES-GFP. After 48 h, cells were stimulated with different concentrations of 5-HT or with 0.5 μm 5-HT in the presence of different inhibitors (SB206553, U73122, U73343, and PTX), followed by calcium imaging. A, B, Time courses of intracellular calcium signals after the addition of 0.5 μm 5-HT in 5-HT2B-expressing cells (A) or in vector-expressing cells (B) at 25 s. The data represent mean values of 10–15 cells. C, The concentration response curve at 5-HT2B receptors. Data points represent the maximum signal (peak values) obtained at each concentration and are mean ± SEM of at least three independent experiments. Each experiment includes 10∼20 cells. D, Histogram showing inhibitor concentration response. Data are mean ± SEM (peak values) of three independent experiments. Comparison between 5-HT- and inhibitor-treated groups (*) was by paired t test: **p < 0.01; ***p < 0.001.