title: Time course of serotonin-induced vasoconstriction.
abstract: Canine cerebral arterial segments tested in a tissue bath were found to escape from the vasoconstrictor effects of serotonin, the basilar segments more rapidly than the middle cerebral segments. At low doses (10(-9) M), serotonin caused a small, prolonged contraction, whereas at higher doses (10(-6) M), a more forceful phasic response was seen. Verapamil blocked the phasic portion of the response but not the low amplitude sustained portion. Increasing the bath concentration of K+, Ba++, and tetraethylammonium markedly enhanced the constrictor response of low serotonin doses and significantly inhibited escape. Potentiation of the force and duration of vasoactive amine-induced arterial constriction by small increments of extracellular K+ might be important in the prolonged vascular narrowing associated with subarachnoid hemorrhage.
mesh_terms: D000818:Animals; D001464:Barium / Q000008:administration & dosage; D002536:Cerebral Arteries / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D008297:Male; D011188:Potassium / Q000008:administration & dosage; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D013757:Tetraethylammonium Compounds / Q000008:administration & dosage; D014661:Vasoconstriction; D014700:Verapamil / Q000008:administration & dosage
chemical_list: D013757:Tetraethylammonium Compounds; D001464:Barium; D012701:Serotonin; D014700:Verapamil; D011188:Potassium