title: Evidence for purinergic receptors on vascular smooth muscle in rat pancreas.
abstract: The changes in flow rate in the isolated pancreas of the rat in response to natural purine nucleotides and phosphate-modified analogues were recorded. ATP and ADP transiently decreased the flow rate in a dose-dependent manner but only at very high concentrations (greater than 165 microM). In contrast, alpha,beta-methylene ATP, the most active of the drugs used, decreased the flow rate of the preparation at very low concentrations: 0.495 microM induced about 50% of the maximum effect. beta, gamma-Methylene ATP and AMP-PNP had an intermediary potency. Pyrophosphate had no effect. AMP and adenosine had no vasoconstrictor effect even at 1650 microM. The vasoconstrictor effect of alpha,beta-methylene ATP was not antagonized by phenoxybenzamine (6 microM) or by apamin (0.01 microM). In contrast PIT, a P2-purinergic receptor antagonist, partially or totally blocked the alpha,beta-methylene ATP effect depending on the concentrations used. From our results it can be concluded that purinergic receptors of P2-type are present on the vascular smooth muscle of the pancreatic bed in the rat.
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D066298:In Vitro Techniques; D007510:Isatin / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000032:analysis* / Q000187:drug effects; D010179:Pancreas / Q000098:blood supply*; D010643:Phenoxybenzamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000032:analysis*; D011983:Receptors, Purinergic
chemical_list: D000227:Adenine Nucleotides; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D010643:Phenoxybenzamine; D001030:Apamin; C009128:2,2'-pyridylisatogen tosylate; D007510:Isatin; D000255:Adenosine Triphosphate; D000241:Adenosine