title: Vascular responses of isolated canine and simian femoral arteries and veins to alpha-adrenoceptor agonists.
abstract: Using isolated, perfused canine and simian femoral veins and arteries, vasoconstrictor responses to 6 alpha-adrenoceptor agonists and to potassium chloride were compared. The order of potencies of alpha-adrenoceptor agonists for inducing constriction was in canine arteries: epinephrine greater than norepinephrine = phenylephrine much greater than clonidine much greater than tyramine much greater than xylazine, in simian arteries: epinephrine greater than norepinephrine greater than phenylephrine greater than clonidine much greater than tyramine greater than or equal to xylazine, in canine veins: epinephrine greater than norepinephrine greater than phenylephrine greater than clonidine greater than or equal to xylazine much greater than tyramine, and in simian veins: norepinephrine = epinephrine greater than phenylephrine greater than clonidine greater than xylazine much greater than tyramine. A selective alpha 2-agonist, xylazine, did not induce any significant constrictor response in canine arteries, indicating a lack of alpha 2-adrenoceptors, but it induced significant constriction in 3 other vessels. In simian femoral arteries and veins dose-response curves to each agonist were steeper than in canine vessels and potassium chloride induced much greater vasoconstriction than in canine vessels, indicating high sensitivity to extracellular calcium concentrations in simian vessels. The cannula inserting method would be useful for investigating pharmacological responses of isolated arteries and veins.
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D005263:Femoral Artery / Q000032:analysis / Q000187:drug effects*; D005268:Femoral Vein / Q000032:analysis / Q000187:drug effects*; D066298:In Vitro Techniques; D008251:Macaca; D011189:Potassium Chloride / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000032:analysis; D013045:Species Specificity
chemical_list: D000316:Adrenergic alpha-Agonists; D011942:Receptors, Adrenergic, alpha; D011189:Potassium Chloride