ZM 241385, an adenosine A(2A) receptor antagonist, inhibits hippocampal A(1) receptor responses

4-(2-[7-amino-2-(2-furyl{1,2,4}-triazolo{2,3 a}-{1,3,5}triazin-5-yl-amino]e thyl)phenol (ZM 241385) has been used as an antagonist of adenosine A(2A) r eceptors, exhibiting high selectivity over adenosine A(1) receptors. We now report that ZM 241385 (10-50 nM) attenuated the inhibitory action of N-6-c yclopentyladenosine (10 nM) and R(-)-N-6-phenylisopropyladenosine (R-PIA, 2 0 nM), two selective adenosine A(1) receptor agonists, on hippocampal popul ation pike amplitude. This effect is unlikely to be a direct antagonism of adenosine A(1) receptor since the K-i of ZM 241385 to displace [H-3]PIA (2 nM) binding, from hippocampal membranes ranged from 0.8 to 1.9 mu M. These results question the usefulness of ZM 241385 to define adenosine A(2A) rece ptors actions in functional studies. (C) 1999 Elsevier Science B.V. All rig hts reserved.