Figure 1.QX-314 inhibition is dependent on TRPV1 expression levels in Xenopus oocytes. Co-application of 15 μM capsaicin with different QX-314 concentrations was flanked by two applications of 15 µM capsaicin to control for (de)sensitization. Only one 10 sec drug application was performed per oocyte with 2 min washout intervals between all applications. (A and C) Representative capsaicin-evoked current traces observed before and after the co-application of (A) 1 µM and (C) 10 µM QX-314 in oocytes expressing low (top panels) or high (bottom panels) levels of TRPV1. Note the different vertical scale bars in top and bottom panels; (B and D) a strong positive correlation is observed between capsaicin-evoked TRPV1 peak current amplitudes (I_max) and the level of inhibition in the presence of 1 µM (B) or 10 µM (D) QX-314. Only oocytes with inward currents I_max > 0.1 µA and < 15 µA were included in the analysis (1 µM QX-314: n = 32; 10 µ MQX-314: n = 38).