Fig. 4

Modulating M-current (IM) pharmacologically affects fictive locomotion evoked by high extracellular potassium in spinalized larval zebrafish. Fictive locomotion was recorded from motor nerves in 4–5 days postfertilization (dpf) spinalized larval zebrafish bathed in artificial cerebrospinal fluid (aCSF) containing a high concentration of potassium (11.6 mM) to promote excitability of spinal locomotor circuits. A: representative traces of fictive locomotion before (control) and after inhibition of IM by 10 µM XE-991. B: representative traces of fictive locomotion before (control) and after enhancement of IM by 10 µM ICA-069673. C: spiking frequency (XE-991: n = 14; ICA-069673: n = 12). D: representative traces of fictive locomotor episodes evoked by high extracellular potassium before and after inhibition of IM by 10 µM XE-991. E: representative traces of fictive locomotor episodes evoked by high extracellular potassium before and after enhancement of IM by 10 µM ICA-069673. F–K: measures of locomotor parameters before and after pharmacological modulation of IM (XE-991: n = 12; ICA-069673: n = 9). F: number of episodes generated per second. G: mean episode duration. H: mean peak amplitude of activity (XE-991: P = 0.0923; ICA-069673: P = 0.4961). I: mean burst frequency (XE-991: P = 0.3804; ICA-069673: P = 0.1641). J: mean number of bursts generated per episode (ICA-069673: P = 0.1289). K: mean burst duration (XE-991: P = 0.1099). L: recording of occlusion experiment where XE-991 was added to the extracellular solution already containing ICA-069673. M: spiking frequency during occlusion experiments (n = 7). Individual animals before and after drug application are color-matched. Statistical analysis, Wilcoxon matched-pairs test (C, F–K) and Friedman test with Dunn’s test for multiple comparisons (M). *P < 0.05, **P < 0.01, ***P < 0.001; otherwise not statistically significant.