Fig. 6.

Single-channel current–voltage relationship of heat- and capsaicin-gated ion channels studied by applying voltage steps between −100 and +40 mV. Pipette solution contained 130 mm NaCl; bath solution contained 130 mm KCl.A, Recordings of heat-induced single-channel events at different membrane potentials in inside-out patch configuration.B, The single-channel I–Vcurve of heat-activated channels in inside-out patches (▪,n = 3), compared with that for whole-cell currents (open circles, n = 5) recorded with the same internal and external solutions. Data for cell-attached patches (data not shown) were superimposable. The curves show outward rectification and reversal potentials close to −20 mV, different from the values given in Table 1, where Cs⁺ was the main internal cation. C, Channel activity in an inside-out membrane patch evoked by perfusion of capsaicin (2 μm) to the inside surface at different membrane potentials. D, The I–V curve of capsaicin induced single-channel current (n = 3) showing the same shape and reversal potential as in B. In single-channel recordings, the dotted line indicates shut state.