title: Agonist-directed trafficking explaining the difference between response pattern of naratriptan and sumatriptan in rabbit common carotid artery.
abstract: 1. Sumatriptan or eletriptan produced vasocontraction in common carotid artery (CCA) by stimulating 5HT(1B) receptors (see also Akin & Gurdal, this issue). 2. Naratriptan as a 5HT(1B/D) agonist, was unable to produce vasocontraction in this artery, but inhibited the vasocontractile response induced by sumatriptan or eletriptan. 3. All these agonists inhibited forskolin-stimulated cyclic AMP production with comparable potencies and maximal responses. This inhibition was mediated by 5HT(1B) receptors: 5HT(1B) antagonist SB216641 (1 microM) completeley antagonized sumatriptan-, eletriptan- or naratriptan-induced cyclic AMP inhibition, but 5HT(1D) antagonist BRL15572 (1 microM) did not affect this response. 4. Naratriptan-induced stimulation of 5-HT(1B) receptors resulted only in adenylate cyclase inhibition, whereas stimulation of these receptors by sumatriptan or eletriptan produced vasocontraction as well. Hence, we concluded that the 5HT(1B)-mediated inhibition of adenylate cyclase was not a sufficient condition to couple the receptor stimulation to vasocontraction. 5. We discussed agonist-induced trafficking as a plausible mechanism for the observed phenomenon.
authors: Department of Pharmacology and Clinical Pharmacology, Medical Faculty of Ankara University, Sihhiye, Ankara 06100 Turkey.
authors: Demet
authors: D
authors: Akin
authors: H Ongun
authors: HO
authors: Onaran
authors: Hakan
authors: H
authors: Gurdal
mesh_terms: D000818:Animals; D017536:Carotid Artery, Common / Q000187:drug effects* / Q000378:metabolism; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D018170:Sumatriptan / Q000494:pharmacology*; D014363:Tryptamines; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology
chemical_list: D007211:Indoles; D010880:Piperidines; D017366:Serotonin Receptor Agonists; D014363:Tryptamines; D018170:Sumatriptan; D000242:Cyclic AMP; C106783:naratriptan