Single-channel ACh-activated currents from fast skeletal muscle of 72-hpf larval zebrafish. (A) A sample ∼0.25-s trace showing two amplitude classes of ACh-activated channels (300 nM) recorded from a cell-attached patch at +30 mV applied potential. The open channel levels for the primary (1°) and secondary (2°) amplitude classes are indicated by the dashed lines. (B) The amplitude frequency histogram for openings recorded from a single patch at +50 mV applied potential. The mean value for each recording (filled symbols) is shown below the sample histogram for both the 1° and 2° classes, along with overall mean values ± SD (open circles). (C) The current–voltage relations for the 1° (black) and 2° (red) single-channel amplitude classes. Each symbol represents the mean amplitude ± SD values of all patches (n = 12) for each applied potential. (D) A burst-duration frequency histogram for the 1° amplitude class from a single recording fit with an exponential function. The mean burst-duration values for each recording of the 1° class (black filled symbols) and 2° class (red filled symbols) are shown along with the overall mean ± SD (open circles) below the histogram. (E) The relationship between applied potential and mean burst duration of the 1° amplitude class is exponential and corresponds to an e-fold change per 122 mV. Each symbol represents the mean ± SD (n = 8 recordings).