NS19504 is a Ca²⁺-activated K⁺ channel (BK channel, KCa1.1 channel) activator (EC₅₀=11.0 µM) with relaxing effect on bladder smooth muscle spontaneous phasic contractions^[1]. IC50 & Target: EC50: 11.0 µM (BK channel)^[1] In Vitro: NS19504 increases BK currents in freshly isolated guinea pig bladder smooth muscle cells and whole-cell. NS19504 increases the whole-cell currents response to 127 %, 194 %, 258 %, 561 % of control at a concentration of 0.32 µM, 1.0 µM, 3.2 µM and 10 µM, respectively^[1].