Fig. 7.

Comparison of the characteristics of single-channel events produced by heat and capsaicin recorded from inside-out patches at −60 mV. Single-channel events were fitted by SCAN and analyzed by EKDIST software. SCAN estimates the amplitudes of single-channel events after correcting for low-pass filtering, and EKDIST plots the frequency distribution of the duration of individual open and closed states. A, E, Single-channel events induced by heat and capsaicin. B,F, Amplitude histogram of channel events, fitted by the maximum likelihood method. Curve fitting reveals a significant number of low-amplitude events, in addition to the main level, for both heat- and capsaicin-evoked activity. Both conductance levels are smaller for capsaicin than for heat (Table 2). C, G, Open time distribution of channel openings induced by heat (C) and capsaicin (G). Both distributions can be fitted by a single component. D,H, Shut time distribution of channel activity produced by heat and capsaicin. In most cases, as here, the fitted distribution indicated the presence of several components, which could not be reliably estimated from the available data. Ordinates of open and shut time distributions are plotted on square root scale, and abscissae are plotted on a logarithmic scale (Colquhoun and Sigworth, 1995).