The effect of the newly synthesized compound 
2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400) on the 
Na+-Ca2+ exchanger (NCX) was investigated and compared against that of 
2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea (KB-R7943). In addition, the 
effects of SEA0400 on reperfusion injury in vitro and in vivo were examined. 
SEA0400 was extremely more potent than KB-R7943 in inhibiting Na+-dependent Ca2+ 
uptake in cultured neurons, astrocytes, and microglia: IC50s of SEA0400 and 
KB-R7943 were 5 to 33 nM and 2 to 4 microM, respectively. SEA0400 at the 
concentration range that inhibited NCX exhibited negligible affinities for the 
Ca2+ channels, Na+ channels, K+ channels, norepinephrine transporter, and 14 
receptors, and did not affect the activities of the Na+/H+ exchanger, 
Na+,K+-ATPase, Ca2+-ATPase, and five enzymes. SEA0400, unlike KB-R7943, did not 
inhibit the store-operated Ca2+ entry in cultured astrocytes. SEA0400 attenuated 
dose- dependently paradoxical Ca2+ challenge-induced production of reactive 
oxygen species, DNA ladder formation, and nuclear condensation in cultured 
astrocytes, whereas it did not affect thapsigargin-induced cell injury. 
Furthermore, administration of SEA0400 reduced infarct volumes after a transient 
middle cerebral artery occlusion in rat cerebral cortex and striatum. These 
results indicate that SEA0400 is the most potent and selective inhibitor of NCX, 
and suggest that the compound may exert protective effects on postischemic brain 
damage.