The Effects of the KCNQ Openers Retigabine and Flupirtine on Myotonia in Mammalian Skeletal Muscle Induced by a Chloride Channel Blocker

Figure 1

Effects of retigabine and flupirtine on the anthracene-9-carboxylic-acid (9-AC)-induced myotonia. Representative muscle contraction traces recorded from mouse phrenic nerve-diaphragm preparations are shown in (a)–(c). The addition of 9-AC (0.1 mM) increased the amplitude of muscle contractions. Treatment with retigabine (0.03 mM, (a)) and flupirtine (0.03 mM, (b)) resulted in an inhibition of the increased amplitude of muscle contractions induced by 9-AC. Lamotrigine (0.03 mM) has no inhibitory effect on the muscle amplitude induced by 9-AC (c). (d) Dose-response effects of retigabine, flupirtine, and lamotrigine on 9-AC-induced myotonia. Percent of control (𝑦-axis): the twitch amplitude ratio of after treatment (retigabine, flupirtine, or lamotrigine) to before treatment (9-AC alone).