FES-evoked relaxations in non-treated and treated guinea pigs. (a) Effect of Hemin (10 µmol.L-1) on 2 Hz (n = 5) evoked relaxations. (b) Effect of Hemin (10 µmol.L-1) on 5 Hz (n = 5) induced relaxatory responses of the strips. Data are the means ±SEM of experiments (* p < 0.5).