Antinociceptive effects of KCNQ channel opener retigabine on visceral pain induced by acetic acid in wild type mice, but not transgenic mice. The onset time (A) and the total number of writhes (B) were determined with vehicle or retigabine (RTG, 7.5 mg/kg) or RTG (7.5 mg/kg) co-injected with XE991 (1 mg/kg) administration (i.p.) before 1% acetic acid (i.p.) injection in both wild type (WT) and transgenic (Tg) groups. Data are expressed as mean ± s.e.m (n = 8-13). RTG (7.5 mg/kg, i.p.) significantly reduced the number of writhes in WT mice, and co-injection of RTG (7.5 mg/kg, i.p.) with XE991 (1 mg/kg, i.p.) reversed the antinociceptive effect of RTG (*p < 0.05).