Endothelin B (ETB) activation increases nighttime suprachiasmatic nucleus (SCN) neuronal activity. (A) Violin plots of spontaneous action potential frequencies of neurons from SCN slices treated with vehicle (water), ETB agonist (IRL-1620, 10 n m) or ET-3 (10 n m). Both treatments significantly increase spontaneous firing rate compared to vehicle (H(2) = 17.842, P < .001). Solid and dotted lines indicate median and quartiles, respectively. n = 133 (vehicle), 146 (IRL-1620), and 130 (ET-3) cells; 3 mice per group. **P = .007, ***P < .001. (B) Representative loose-patch traces (5 s) from each group. Scale bars: 2 s, 50pA. (C) Percentage of silent (empty bars) versus spiking (filled bars) for cells differed between groups (χ2(2) = 13.529, P = .001), with significantly more silent cells in ET-3-treated slices compared to vehicle (P < .05).
