Figure 1.
Effect of DTX and/or XE991 on single spiking in developed M cells. A, Firing response of M cells at 4–7 dpf [upper three rows of traces elicited by step depolarizing currents (lower traces) of 1×, 1.5×, and 2× threshold intensity (T), as represented in nA on 1T traces] before and after bath application of either 100 nM DTX, 10 μM XE991, or both. B, Initial phase of repetitive firing in response to 2T current injection recorded from M cells with DTX and XE991 treatment, and untreated (control) MiD2cm and MiD3cm cells at 4 dpf. C, Number of APs elicited during a depolarizing current pulse (100 ms) plotted against current intensity (T). The number of APs significantly increased after combined DTX and XE991 treatment compared with each separately. D, Summary data for the ISI of repetitive firing in response to 2T current injection against the interval number. After combined DTX and XE991 treatment, M cells at 4–7 dpf exhibited ISIs that were similar to untreated MiD2cm and MiD3cm cells at the same developmental stage. E, F, The effect of DTX and/or XE991 on threshold current (E) and onset latency of the first spike at 1T (F). Treatment of DTX, but not XE991, reduced the threshold current and increased spiking latency of M cells. n.s., not significant. *p < 0.05, **p < 0.01, Mann–Whitney U test (control, n = 14; +DTX, n = 8; +XE991, n = 7; +DTX + XE991, n = 6). Two-way repeated measures ANOVA was used for ISI (MiD2cm, n = 8; MiD3cm, n = 7).