VUF 5574 is an antagonist of the adenosine A3 receptor (Ki = 4.03 nM for the recombinant human receptor). It is greater than 2,500-fold selective for adenosine A3 over A1 and A2A receptors. VUF 5574 (100 nM) decreases phosphorylation of ERK1/2 induced by adenosine in isolated porcine coronary artery smooth muscle cells. It increases oxygen-glucose deprivation-induced reductions in the amplitude of field excitatory postsynaptic potentials (EPSPs) in a rat hippocampal slice model of ischemia when used at a concentration of 100 nM. VUF 5574 (2 μg, intracisternal) reduces sodium nitroprusside-induced heart rate increases in rats.