title: Evidence against adenylate cyclase-coupled adenosine receptors in the guinea pig heart.
abstract: (--)-N6-(Phenylisopropyl)adenosine (PIA, 10 microM) and 5'-N-(ethylcarboxamide)adenosine (NECA, 50 microM), potent agonists at the adenylate cyclase-coupled R-site adenosine receptor, were investigated for adenylate cyclase inhibition in a guinea pig ventricular membrane preparation by means of the dATP assay method. Neither compound influenced basal or isoproterenol-stimulated cyclase activity, irrespective of whether Na ions were present or not. These data suggest that R-site receptors may not be involved in the cardiac adenylate cyclase system of the guinea pig.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009206:Myocardium / Q000201:enzymology*; D011956:Receptors, Cell Surface / Q000187:drug effects*; D011983:Receptors, Purinergic
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D000241:Adenosine