title: alpha 1-Antagonist activity of the alpha 2-adrenoceptor agonist guanabenz in perfused mesenteric artery of the rat.
abstract: In the perfused mesenteric artery of the rat phenylephrine produced a concentration-dependent increase in perfusion pressure which was competitively antagonized by low concentrations of prazosin (pA2 9.56). Guanfacine, clonidine and guanabenz, three alpha 2-selective agonists, produced no response. However, guanabenz antagonized the phenylephrine-induced effect competitively (pA2 6.92) though guanfacine and clonidine did not affect it. These results suggest that the alpha 2-adrenergic agonist guanabenz possesses alpha 1-antagonist activity as well.
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology; D005260:Female; D006143:Guanabenz / Q000494:pharmacology*; D016316:Guanfacine; D006146:Guanidines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects*; D010477:Perfusion; D010648:Phenylacetates / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
chemical_list: D006146:Guanidines; D010648:Phenylacetates; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D016316:Guanfacine; D006143:Guanabenz; D003000:Clonidine