BW-A522 BLOCKS ADENOSINE A(3) RECEPTOR-MEDIATED HYPOTENSIVE RESPONSESIN THE RAT

The effects of o-4-aminobenzyl)-8-(4-oxyacetate)-1-propylxanthine (I-A BOPX; BW-A522), which has nanomolar affinity for the recently cloned h uman and sheep adenosine A(3) receptor, on the putative A(3) receptor mediated hypotensive response to N-6-2-(4-aminophenyl)ethyl adenosine (APNEA) in the rat have been investigated. Following blockade of A(1) and A(2) receptors with 8-(p-sulphophenyl)theophylline, BW-A522, 10 an d 40 mg/kg i.v., blocked dose-dependently and surmountably the hypoten sive response to APNEA. The results provide direct evidence of an A(3) receptor in the cardiovascular system of the rat which induces hypote nsion when activated.