LAMOTRIGINE INHIBITS DEPOLARIZATION-EVOKED CA++ INFLUX IN DISSOCIATEDAMYGDALA NEURONS

Spectrophotometry with the Ca++-sensitive dye fura-2 was used to study the effect of lamotrigine (LAG) on the depolarization-evoked Ca++ inf lux in the acutely isolated basolateral amygdala neurons. Depolarizati on of the neurons with high K+ resulted in the elevation of intracellu lar Ca++ concentration [Ca++](i) in a concentration-dependent manner. The K+-induced Ca++ influx was completely blocked in the Ca++-free sol ution or by Cd++, indicating that depolarization-induced increases in [Ca++](i) were triggered largely, if not at all, by Ca++ entry from ex tracellular space and Ca++ entry occurred through voltage-dependent Ca ++ channels. Application of LAG reduced the depolarization-evoked Ca+ influx in a concentration-dependent manner. The effect of LAG was mar kedly reduced in the presence of N-type Ca++ channel blocker omega-con otoxin-GVIA (omega-CgTX), These results suggest that the action of LAG is mediated, at least in part, by the modulation of N-type Ca++ chann els. Synapse 29:355-362, 1998. (C) 1998 Wiley-Liss, Inc.