Fig. 3. Outside-out single-channel currents fromXenopus oocytes expressing α3β4, α4β2, and α4β2E260 do not show inward rectification.A, C, and E show steady-state single-channel recordings from outside-out patches of oocytes expressing α3β4, α4β2, or α4β2E260, respectively. These recordings were performed in the continuous presence of ACh: 100–200 nm for α4β2 and α4β2E260 and 1–2 μm for α3β4. Numbers on theleft of each trace correspond to the holding potential at which that recording was obtained. The dotted linesmark the zero current level for each trace. B,D, and F show the single-channelI–V plots for α3β4, α4β2, or α4β2E260, respectively. TheseI–V plots, in contrast to the corresponding macroscopic I–V plots (Fig. 2A,C,E), show a slight outward rectification. Each point in the plots represents the mean ± SE of single-channel current amplitudes from four patches for α3β4, eight patches for α4β2, and eight patches for α4β2E260.