title: Characterization of contractile adrenoceptors in the human umbilical artery.
abstract: Adrenoceptors mediating contraction in ring segments of human umbilical arteries from normal term pregnancies were investigated in vitro. Contraction was elicited by (order of potency indicated): noradrenaline = the alpha 2-adrenoceptor agonist oxymetazoline >> the alpha 1-adrenoceptor agonist phenylephrine. The alpha 1-adrenoceptor antagonist prazosin antagonized the contraction elicited by noradrenaline and phenylephrine. The alpha 2-adrenoceptor antagonist rauwolscine antagonized the contraction elicited by noradrenaline and oxymetazoline. Oxymetazoline had an efficacy 5 times higher than that of noradrenaline and the 5-hydroxytryptamine receptor antagonist methysergide antagonized the contraction elicited by oxymetazoline. It is suggested that the contractile adrenoceptors in the human umbilical artery consist of both alpha 1 and alpha 2 subtypes. Furthermore, the contractile effect of oxymetazoline seems to be mediated via both alpha 2-adrenoceptors and 5-hydroxytryptamine receptors.
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology*; D009647:Normetanephrine / Q000494:pharmacology; D010100:Oxygen / Q000097:blood*; D010109:Oxymetazoline / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011247:Pregnancy; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000502:physiology*; D014469:Umbilical Arteries; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D000316:Adrenergic alpha-Agonists; D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D009647:Normetanephrine; D010656:Phenylephrine; D010109:Oxymetazoline; D011433:Propranolol; D003042:Cocaine; D010100:Oxygen; D009638:Norepinephrine