LPA produces an increase in single-channel currents in TRPV1 channels heterologously expressed in HEK293. (A–D) Representative traces from single-channel recordings of TRPV1 channels in the inside-out configuration, as compared with capsaicin. The letters c and o represent the closed and open state levels shown in the histograms. The vertical dotted lines represent the average single-current amplitude elicited by capsaicin (6.84 ± 0.23 pA; n = 24) before the application of treatment. (A) Capsaicin 4 µM + BSA 0.0005% (6.57 ± 1 pA; n = 4). (B) LPA 5 µM in BSA 0.0005% (9.66 ± 0.23 pA; n = 10). (C) BrP-LPA 5 µM (8.97 ± 0.27 pA; n = 6). (D) Capsaicin 5 µM + 2.5 µM LPC (7.34 ± 0.41 pA; n = 3). (E) Summary of the results in A–D. Lines between the symbols indicate average ± SEM. *, statistical significance P 0.01. The fold increase in current amplitude in each case is as follows: capsaicin + BSA, 0.96 ±0.16; LPA 5 µM, 1.41 ± 0.03; BrP-LPA 5 µM, 1.31 ± 0.04; and LPC 2.5 µM + capsaicin 4 µM, 1.07 ± 0.05. Recordings were made applying a series of 1-s-long, 60-mV square pulses from a 0-mV holding potential; data were sampled at 50 kHz and filtered with at 3-kHz low-pass Bessel filter. Each seal was exposed to 4 µM capsaicin, washed, and then exposed to the indicated lipid by perfusion using a rapid solution changer.