Single-channel currents of human α4β2 display multiple conductance levels at low and high ACh concentrations.A, Portion of 800 msec recordings performed with a single patch have been enlarged to illustrate the different current amplitudes that could be observed. The thick horizontal bars above top traces indicate the applications of ACh. The thin dashed lines correspond to conductance levels of 0, 40, and 80 pS from top tobottom. B, Cumulative all-point amplitude histograms computed from several traces obtained in the same patch (the bin was set at 0.1 pA) were normalized to the total number of events in each recording condition (20 sweeps recorded in 100 nm ACh and 14 recorded in 30 μm ACh). The barscorresponding to the setup noise have been truncated to present the current amplitudes at a higher resolution. Note the increase of the low conductance event number when openings are elicited by a 30 μm ACh concentration. This observation has been repeated in all patches recorded in both ACh concentrations (n = 7).