Selective Na + /Ca 2+ -exchange (NCX) inhibitor; displays some selectivity for NCX1. IC 50 values are 2.9, 16 and 8.6 μ M for inhibition of intracellular Na+-dependent 45 Ca 2+ uptake by cells expressing NCX1, NCX2 and NCX3 respectively. Has some affinity for mACh receptors (IC 50 = 18 μ M) but minimal activity against NCKX2 and various receptors and ion channels (IC 50 > 30 μ M). Preferentially blocks Ca 2+ influx mode and is more selective for NCX isoforms than KB-R7943 (2-[2-[4-(4-Nitrobenzyloxy)phenyl]ethyl]isothioureamesylate ). Anti-ischemic; potently protects against hypoxia-induced renal tubular cell damage (IC 50 = 0.63 μ M).