Fig. 4. Open channel blockade of lamotrigine on 5-HT₃ receptor.

(A) Sample traces show the 5-HT (open bar, 10 µM) and 5-HI (gray bar, 1 mM)-evoked currents and the effects of subsequent treatment of lamotrigine (LTG) on these current (closed bar). The residual currents (time indicated by ▲) after the application of lamotrigine were analyzed for the evaluation of inhibitory effects. (B) Concentration–response relationship of the lamotrigine (1, 3, 10, 30, 100 and 300 µM) on 5-HT₃ receptor currents evoked by the co-application of 5-HT (10 µM) and 1 mM of 5-HI (n=9). Data were normalized to the value of the residual currents measured at the indicated timing in the 5-HT₃ receptor currents induced by 10 µM of 5-HT and 1 mM of 5-HI, which was taken as 1. Each data represents mean±S.E.M.