title: Species-dependent effects of adenosine receptor agonists on contractile responses of vas deferens to ATP.
abstract: 1. Experiments were carried out to examine the postjunctional actions of adenosine receptor agonists on the smooth muscle of the vas deferens of the guinea-pig and rabbit. 2. Although they produced neither contraction nor relaxation by themselves, adenosine analogues enhanced contractions of the guinea-pig vas deferens induced by 10 microm ATP. The rank order of potency was N6-cyclopentyladenosine (CPA) > 5'-N-ethylcarboxamidoadenosine (NECA) > adenosine > CGS 21680. Dose-response curves for NECA were shifted to the right by the nonselective adenosine receptor antagonist 8(p-sulphophenyl)theophylline (8-SPT; 100 microM) and by the selective A1-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 1 mM). 3. In the rabbit vas deferens, contractions induced by ATP (1 mM) were inhibited rather than facilitated by NECA. Neither CPA, R(-)-N6-(2-phenyl isopropyl)-adenosine (R-PIA) nor CGS 21680 had any effect. 4. The results indicate that the smooth muscle of the guinea-pig vas deferens expresses facilitatory adenosine A1 receptors but not adenosine A2 receptors. In contrast, in rabbit there are postjunctional inhibitory adenosine A2A receptors but not adenosine A1 receptors.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Nevada, Reno 89557, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Moloney
authors.forename: M A
authors.initials: MA
authors.lastname: Khoyi
authors.forename: D P
authors.initials: DP
authors.lastname: Westfall
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000818:Animals; D006224:Cricetinae; D015226:Dinucleoside Phosphates / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009469:Neuromuscular Junction / Q000187:drug effects*; D010627:Phenethylamines / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D011817:Rabbits; D018047:Receptors, Purinergic P1 / Q000145:classification; D013045:Species Specificity; D014649:Vas Deferens / Q000187:drug effects*
chemical_list: D015226:Dinucleoside Phosphates; D010627:Phenethylamines; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C013907:cytidylyl adenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D000241:Adenosine