Log concentration-response relaxation curves to adenosine, 5′-N-ethylcarboxamidoadenosine (NECA), N6-cyclopentyladenosine (CPA), 5′-(N-cyclopropyl)-carboxamidoadenosine (CPCA), 2-chloroadenosine (2-CA), N6-(3-iodobenzyl)-adenosine-5′-N-methylcarboxamide (IB-MECA) and 2-[p-(carboxyethyl)-phenylethylamino]-5′-N-ethylcarboxamidoadenosine (CGS21680), in pig intravesical ureteral strips contracted to 10−7 M U46619. Relaxations are expressed as a percentage of the U46619-induced contraction. Results represent means and vertical line s.e. of the mean of 5–17 preparations.