Inhibitory effect of adenosine on electrically evoked contractions in the rat vas deferens: Pharmacological characterization

Abstract

The inhibitory effects of adenosine as well as its related analogues on the contractile response of the rat vas deferens to field stimulation were compared in the absence and in the presence of nitrobenzylthioguanosine (NBTGR), a potent adenosine uptake inhibitor. In the presence of NBTGR, the order of potency was N 6- cyclohexyladenosine(CHA) ≧ l-N 6- phenylisopropyladenosine( l-PIA) > 2- chloroadenosine > d-N 6- phenylisopropyladenosine ( d-PIA) ≧ adenosine > 2′- deoxyadenosine . The inhibitory effect of adenosine but not that of clonidine, β-endorphin and somatostatin was blocked by 1,3-diethyl-8-phenyl-xanthine (DPX, pA 2 = 7.2), a potent P 1-purinergic antagonist. The results suggest that adenosine inhibited the electrically evoked contractions of the rat vas deferens via the activation of the A 1 subtype of P 1-purinergic receptors.