Calmidazolium (chloride) is an inhibitor of calmodulin (CaM), inhibiting CaM-dependent phosphodiesterase and CaM-induced activation of erythrocyte calcium-transporting ATPase (IC50 = 0.15 and 0.35 μM, respectively). Calmidazolium also inhibits an array of calcium-transporting ATPases, including those from heart and skeletal muscle (IC50 = 2.1 and 2.9 μM, respectively). It also induces the influx of extracellular calcium through store-operated calcium channels (EC50 = 3 μM).
