Sodium-hydrogen exchanger isoform-1 (NHE-1) inhibitor that displays selectivity over other NHE isoforms (Ki values are 14, 2200 and 220000 nM for human NHE-1, human NHE-2 and rat NHE-3 respectively). Inhibits NHE-1 dependent 22Na+ uptake in vitro (IC50 = 14 nM) and provides cardioprotection from myocardial ischemic injury in vivo (EC50 = 0.25 nM).