title: Cytosolic Ca2+ oscillations in REF52 fibroblasts: Ca(2+)-stimulated IP3 production or voltage-dependent Ca2+ channels as key positive feedback elements.
abstract: Oscillations in cytosolic free calcium concentrations ([Ca2+]i) can be elicited in REF52 fibroblasts by three different modes of stimulation. We have previously demonstrated that [Ca2+]i oscillations result when these cells are simultaneously depolarized and stimulated with a hormone linked to phosphoinositide breakdown. Further evidence is now presented that such oscillations are linked to fluctuations in the concentration of IP3 and the Ca2+ content of an IP3-sensitive Ca2+ store. [Ca2+]i oscillations can also be generated in REF52 cells either by direct stimulation of G-proteins with GTP gamma S or AlF4- or by destabilizing the membrane potential and opening voltage-dependent calcium channels. This report compares the different types of oscillations and their mechanisms.
authors.affiliation: Howard Hughes Medical Institute, University of California San Diego, La Jolla.
authors.forename: A T
authors.initials: AT
authors.lastname: Harootunian
authors.forename: J P
authors.initials: JP
authors.lastname: Kao
authors.forename: S
authors.initials: S
authors.lastname: Paranjape
authors.forename: S R
authors.initials: SR
authors.lastname: Adams
authors.forename: B V
authors.initials: BV
authors.lastname: Potter
authors.forename: R Y
authors.initials: RY
authors.lastname: Tsien
mesh_terms: D000814:Aniline Compounds; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000187:drug effects*; D002460:Cell Line / Q000187:drug effects; D002468:Cell Physiological Phenomena; D003600:Cytosol / Q000502:physiology*; D004075:Diglycerides / Q000494:pharmacology; D005246:Feedback / Q000187:drug effects; D005347:Fibroblasts; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism* / Q000031:analogs & derivatives; D007295:Inositol Phosphates / Q000494:pharmacology; D008564:Membrane Potentials; D009946:Organothiophosphorus Compounds / Q000494:pharmacology; D010507:Periodicity; D010782:Photolysis; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014966:Xanthenes
chemical_list: D000814:Aniline Compounds; D015220:Calcium Channels; D004075:Diglycerides; D007295:Inositol Phosphates; D009946:Organothiophosphorus Compounds; D013729:Terpenes; D014966:Xanthenes; C044295:1,2-dioctanoylglycerol; C054737:inositol 1,4,5-triphosphorothioate; C059715:Fluo-3; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium