title: Arachidonic acid and other unsaturated fatty acids alter membrane potential in PC12 and bovine adrenal chromaffin cells.
abstract: The action of arachidonic acid and other fatty acids on membrane potential in PC12 and bovine chromaffin cells was investigated using a membrane potential-sensitive fluorescent dye. Arachidonic acid (1-40 microM) provoked dose-dependent membrane hyperpolarization, thereby reducing hyperpolarization induced by the K(+)-selective ionophore valinomycin. Other cis-unsaturated fatty acids, but not lipoxygenase products or the saturated fatty acid palmitic acid, also affected membrane potential. Tetraethylammonium blocked the arachidonic acid-induced hyperpolarization. These data suggest that cis-unsaturated fatty acids alter membrane potential in PC12 and bovine chromaffin cells by modulating K+ conductances. Valinomycin-generated hyperpolarization had no effect on agonist-induced Ca2+ influx into bovine chromaffin cells, whereas preincubation with arachidonic acid and other cis-unsaturated fatty acids blocked Ca2+ influx and secretion. We propose a model where internally generated fatty acids act as a feedback to desensitize the stimulated cell via inhibition of receptor-dependent Ca2+ influx and induction of membrane hyperpolarization.
authors.affiliation: Theodor Kocher Institute, University of Berne, Switzerland.
authors.forename: M U
authors.initials: MU
authors.lastname: Ehrengruber
authors.forename: D A
authors.initials: DA
authors.lastname: Deranleau
authors.forename: C
authors.initials: C
authors.lastname: Kempf
authors.forename: P
authors.initials: P
authors.lastname: Zahler
authors.forename: M
authors.initials: M
authors.lastname: Lanzrein
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002838:Chromaffin System / Q000166:cytology / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D016716:PC12 Cells / Q000187:drug effects* / Q000502:physiology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D005231:Fatty Acids, Unsaturated; D016859:Lipoxygenase Inhibitors; D014634:Valinomycin; D016718:Arachidonic Acid; D002118:Calcium