Figure 4

PME suppresses I _CAP in transfected HEK293 cells. A, B: Representative trace shows I_CAP (capsaicin, 20 nM) in the absence (A) or presence (B) of PME (30 μM). Cells were perfused for 2 min with solution containing PME before reapplication of the capsaicin (CAP). C: PME inhibit I_CAP dose dependently. Numbers in parentheses indicate cells tested. ** p < 0.01 versus 0 μM PME, one-way ANOVA followed by Fisher’s PLSD. D: I_CAP concentration-response curves for TRPV1 activation in the absence (open circles) or presence (filled circles) of PME (30 μM). Currents were normalized to the currents maximally activated by 1 μM capsaicin (CAP) in the absence of PME. The figure shows averaged data fitted to the Hill equation. EC₅₀ = 42.6 nM and EC₅₀ = 148.2 nM in the absence or presence of PME, respectively. Calcium-free extracellular solutions were used to prevent TRPV1 desensitization in all experiments. Cells were perfused with capsaicin (20 nM) until the current reaching peak.