Selective KCa2 (SK) channel negative modulator; inhibits SK channel currents (Kd values are 0.42, 0.6 and 0.73 μM for SK1, SK2 and SK3 respectively at 0.5 μM Ca2+). Exhibits selectivity for SK channels over KCa1.1 (BK), KCa3.1 (IK), Kv, Nav and Cav channels. Inhibits afterhyperpolarization in hippocampal slices. Purity 98%. MW (observed): 299.8