Single-channel gating of TRPV1 channels with capsaicin or LPA. (A) Representative segments of single-channel records in the presence of capsaicin 4 µM. The dashed and dotted lines represent the zero-current level and the current level when the same channel is opened by LPA, respectively. (B) Burst length distribution. The continuous line on top of the histogram is the fit to a sum of three exponentials, which are shown individually by the gray dotted lines. (C) A single TRPV1 channel opened by LPA 5 µM. Representative openings with the dashed and dotted lines indicating zero-current and open current levels, respectively. (D) Burst length distribution. The continuous line on top of the histogram is the fit to a sum of three exponentials, which are shown individually by the gray dotted lines. (E) Representative segments of a single-channel recording with subsaturating 50 nM capsaicin. Lines have the same meaning as in A. (F) Burst length distribution. The continuous line on top of the histogram is the fit to a sum of three exponentials, which are shown individually by the gray dotted lines. (G) Recordings from a single channel activated by 1 µM LPA. The lines indicate current levels as in C. (H) Burst length distribution. The continuous line on top of the histogram is the fit to a sum of three exponentials, which are shown individually by the gray dotted lines. The parameters of the exponential fits are compiled in Table 1. Recordings were made applying up to 100 3-s-long, 60-mV square pulses from a 0-mV holding potential; data were sampled at 50 kHz and filtered with a 3-kHz low-pass Bessel filter. Capsaicin and LPA were applied by perfusion with a rapid solution changer.