High affinity, selective KCa2.2 (SK2) channel blocker (Kd = 3.8 nM). Exhibits >200-fold selectivity for KCa2.2 over KCa2.1, KCa2.3, KCa3.1, IK, Kv and Kir2.1. Increases theta-burst responses and increases LTP in rat hippocampal slices in vitro. Convulsive in vivo. MW (observed): 3392.06.