A_2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission

摘要

1. The present study was designed to characterize the adenosine receptors involed in the relaxation of the pig intravesical ureter, and to investigate the action of adenosine on the non adrenergic non cholinergic (NANC) excitatory ureteral neurotransmission. 2. In U46619 (10~-7 M)-contracted strips treated with the adenosine uptake inhibitor, nitroben- zylthioinosine (NBTI, 10~-6 M), adenosine and related analogues induced relaxatins with the following potency order: 5'-N-ethylcarboxamidoadenosine (NECA) = 5'-(N-cyclopropyl)-carboxami- doadenosine (CPCA) = 2-chloroadenosine (2-CA)>adenosine >cyclopentyladenosine (CPA) = N~6-(3- iodobenzyl) adenosine-5'-N-methylcarboxamide (IB-MECA) = 2-[p-(carboxyethyl)-phenylethylami- no]-5'-N-ethylcarboxamidoadenosine (CGS21680).