title: Alpha 1-adrenoceptor subtype(s) mediating noradrenaline-induced contractions of the guinea-pig aorta.
abstract: The effect of alpha 1-adrenoceptor subtype selective antagonists, WB 4101, SZL-49 and chloroethylclonidine on noradrenaline-induced contractions of the guinea-pig aorta has been studied in an attempt to identify the alpha 1-adrenoceptor subtype(s) involved in the response. Noradrenaline and SDZ NVI 085 induced contractions of the aorta. Noradrenaline-induced contractions were competitively antagonised by WB 4101 (pA2 = 8.92, slope = 1.05). The contractions were significantly reduced by SZL-49 but not by chloroethylclonidine, indicating an action on alpha 1A-adrenoceptor subtype. Noradrenaline-induced contractions of the aorta were not inhibited by nifedipine (10(-6) M). The results are interpreted to suggest that alpha 1A-adrenoceptor subtype mediates noradrenaline-induced contractions of the guinea-pig aorta and that activation of alpha 1A-adrenoceptor subtype in the guinea-pig aorta is probably linked to intracellular Ca++ release.
authors.affiliation: Department of Pharmacology & Toxicology, Faculty of Medicine, Kuwait University, Safat.
authors.forename: M A
authors.initials: MA
authors.lastname: Oriowo
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology; D001952:Bridged-Ring Compounds; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D010078:Oxazines / Q000494:pharmacology; D011224:Prazosin / Q000031:analogs & derivatives / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D001643:Bridged Bicyclo Compounds; D001952:Bridged-Ring Compounds; D004146:Dioxanes; D010078:Oxazines; D018340:Receptors, Adrenergic, alpha-1; C074349:SDZ NVI-085; C051307:SZL 49; C051731:chlorethylclonidine; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D009543:Nifedipine; D003000:Clonidine; D009638:Norepinephrine; D011224:Prazosin