Potent and highly selective agonist at A1 adenosine receptors (Ki values are 3.3, 9580, 37600 and 1150 nM for human recombinant A1, A2A, A2B and A3 receptors respectively). Acts as a full agonist; inhibits forskolin-stimulated adenylyl cyclase activity in rat cortical membranes with an IC50 value of 13.1 nM.