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. 2021 Jan 17;296:100302. doi: 10.1016/j.jbc.2021.100302

Figure 4.

Figure 4

A supratherapeutic concentration of 100-μM 3,4-DAP significantly broadens the frog presynaptic AP waveform independent of Cav1 channels.A, normalized presynaptic AP waveform splines recorded from a nerve terminal before (black) and after (red) the addition of 100-μM 3,4-DAP. B, the normalized average of all predrug (black) and post–100-μM 3,4-DAP (red) presynaptic AP waveform splines recorded from all frog motor nerve terminals (n = 10). C, FWHMs of recorded AP waveforms before (circles) or after (triangles) 100-μM 3,4-DAP application to vehicle (pink) or nitrendipine (blue) treated frog NMJs. 100-μM 3,4-DAP broadens the AP waveform independent of nitrendipine (two-way mixed ANOVA: significant main effect of 100-μM 3,4-DAP (F (1,8) = 524.7, ∗∗∗p < 0.0001), but no main effect of nitrendipine (F (1,8) = 2.035, p = 0.1916), and no interaction between 3,4-DAP and nitrendipine (F (1,8) = 2.292, p = 0.1685); vehicle, n = 6; nitrendipine, n = 4). D and E, plots of individual paired recorded values (gray dotted lines) of AP duration (FWHM) before and after application of 1.5-μM 3,4-DAP with a superimposed average (vehicle, solid pink line; nitrendipine, solid blue line). 3,4-DAP, 3,4-diaminopyridine; AP, action potential; Cav, voltage-gated calcium; FWHM, full width at half maximum.