title: Role of eicosanoids in vasopressin-induced calcium mobilization in A7r5 vascular smooth muscle cells.
abstract: The role of arachidonic acid (AA) and its metabolites in vasopressin (AVP)-induced calcium mobilization in A7r5 aortic smooth muscle cells was explored by intracellular calcium monitoring, [14C]AA labeling, and high-performance liquid chromatography (HPLC) techniques. In fura 2-loaded A7r5 cells, AA potentiated AVP-stimulated increase in intracellular free Ca2+ ([Ca2+]i). The cyclooxygenase inhibitor indomethacin reduced both the AA- and AVP-induced influx of extracellular Ca2+. AVP-induced [Ca2+]i transients were not altered by lipoxygenase inhibitors but were reduced in a dose-dependent fashion by ketoconazole, an inhibitor of cytochrome P-450 monooxygenases. Among several epoxygenase metabolites of AA tested, 5,6-epoxyeicosatrienoic acid potentiated AVP-induced [Ca2+]i transients. Reverse-phase HPLC analysis of lipid extracts from A7r5 cells prelabeled with [14C]AA isolated a radioactive peak that did not coelute with established products of cyclooxygenase-, lipoxygenase-, or cytochrome P-450-catalyzed oxidations of AA. This peak was significantly increased after AVP stimulation and was completely blocked by preincubation with ketoconazole. Thus the stimulation of V1-vascular AVP receptors of A7r5 cells triggers several cytoplasmic signaling pathways involving AA metabolite formation through the cyclooxygenase and epoxygenase pathways.
authors.affiliation: Department of Medicine, University Hospitals of Cleveland, Ohio.
authors.forename: M
authors.initials: M
authors.lastname: Thibonnier
authors.forename: A L
authors.initials: AL
authors.lastname: Bayer
authors.forename: C L
authors.initials: CL
authors.lastname: Laethem
authors.forename: D R
authors.initials: DR
authors.lastname: Koop
authors.forename: M S
authors.initials: MS
authors.lastname: Simonson
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism / Q000502:physiology; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D015777:Eicosanoids / Q000502:physiology*; D004594:Electrophysiology; D007213:Indomethacin / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism; D007654:Ketoconazole / Q000494:pharmacology; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000502:physiology
chemical_list: D015777:Eicosanoids; D016859:Lipoxygenase Inhibitors; D001127:Arginine Vasopressin; D016718:Arachidonic Acid; D007654:Ketoconazole; D002118:Calcium; D007213:Indomethacin