Figure 8

TDAG8 activation sensitizes TRPV1 response to capsaicin. (A-G) HEK293T cells were transfected with TDAG8-pIRES-GFP, TRPV1-pIRES-GFP, or both plasmids. After 36 hours, cells were exposed to pH 7.4, 6.4 or vehicle for 15 or 30 minutes at 37°C or at 22°C and then washed with pH7.4 buffer, followed by addition of 5 nM of capsaicin at room temperature. Time courses of [Ca²⁺]_i signals following addition of different agonists (A-F). Intracellular [Ca²⁺] change in HEK293T cells (G). Peak values of [Ca²⁺]_i response (approximately 20 seconds after the addition of agonists) are presented as histograms. All data are presented as mean ± SEM (n = 14–23 cells). Comparison between TRPV1 and TRPV1/TDAG8-transfected cells was by t test, ***p < 0.005. (H) Intracellular [Ca²⁺] change in DRG cultures. Primary DRG cultures were transiently exposed to different concentrations of capsaicin or pH6.4 at room temperature. Some cultures were pre-treated with pH6.4 buffer for 30 minutes at 37°C and then washed with pH7.4 buffer, followed by addition of 5 nM of capsaicin at room temperature. Peak values of [Ca²⁺]_i response (approximately 20 seconds after the addition of agonists) are presented as histograms. All data are presented as mean ± SEM (n = 12–18 cells).