Figure 6.
The effects of 20 nm TTX on respiratory rhythm in vitro. A, XII output is shown in control, 20 nm TTX (15 and 20 min elapsed time), and recovery conditions. B, Evoked action potentials in control and 20 nm TTX conditions. Baseline VM was -60 mV. The calibration bar applies to both VM and stimulus current (Ia). C, Bar charts showing the mean effects of TTX on cellular and systems level respiratory activity (n = 9 mouse slices tested). Frequency in TTX was taken as the average of three to five bursts just before TTX-induced cessation of the rhythm. The amplitude of XII motor output is scaled in arbitrary units (a.u.). Rheobase and spike “active fraction” are defined in Results. Error bars indicate SEM for n = 9 mouse slice preparations. Single asterisk indicates statistical significance at p < 0.01, and double asterisk indicates p < 0.005.