Description_x000D_ Biochem/physiol Actions_x000D_ Synta66 (S66) is a CRAC (Ca2+ release-activated Ca2+) channel inhibitor that blocks SOCE (store-operated Ca2+ entry) upon Ca2+ depletion from intracellular stores by thapsigargin in human vascular smooth muscle cells (VSMCs) with high potency (IC50 = 26 nM & 43 nM based on maximum Ca2+ level & rate of increase, respectly). Synta66 exhibits no affinity toward a range of receptors and ion channels (e.g. L-type Ca2+ channel) and does not affect TRPC1/5-mediated SOCE or store-operated non-selective cationic current. Leukocytes are reported to be less sensitive to CRAC inhibition by Synta66 (IC50 = 1.76 μM/HL-60, 1 ?M/Jurkat, 1.4 μM/rat RBL).