INHIBITION OF N-TYPE CALCIUM CURRENTS BY LAMOTRIGINE IN RAT AMYGDALARNEURONS

Lamotrigine (LAG) is a new anticonvulsant drug for the treatment of pa rtial and secondarily generalized seizures. The present study was aime d at elucidating the possible involvement of Ca2+ channels in the acti on of LAG using whole-cell patch clamp recordings in acutely dissociat ed amygdalar neurones. Whole-cell Ca2+ currents (I-Ca) were elicited b y 200 ms step commands from -70 mV to -10 mV. Application of LAG reduc ed the I-Ca by an average of 40.3 +/- 3.2% The inhibition of I-Ca by L AG was markedly reduced or eliminated in the presence of the N-type Ca 2+ channel blocker omega-conotoxin-GVIA (1 mu M). These results sugges t that LAG may exert its anticonvulsant effect through inhibition of p resynaptic N-type Ca2+ channels, thereby reducing glutamate release.