title: Effect of a prolonged glutamate challenge on plasmalemmal calcium permeability in mammalian central neurones. Mn2+ as a tool to study calcium influx pathways.
abstract: The rate of Mn(2+)-induced fluorescence quenching (RFQ) was used as a relative measure of plasma membrane Ca2+ permeability (PCa) in fura-2-loaded cultured hippocampal neurons and cerebellar granule cells during and after protracted (15-30 min) glutamate (GLU) treatment. Some limitations of this method were evaluated using a kinetic model of a competitive binding of Mn2+ and Ca2+ to fura-2 in the cell. In parallel experiment a contribution of Ca2+ influx to the cytoplasmic Ca2+ ([Ca2+]i) was repeatedly examined during and following a prolonged GLU challenge by short-duration "low-Ca2+ trials" (50 microM EGTA) and by measurements of 45Ca2+ uptake. Experiments failed to reveal a putative persistent increase in PCa that earlier was thought to underlie Ca2+ overload of the neuron caused by its toxic GLU treatment. By contrast, a sustained increase of [Ca2+]i was found to be associated with a progressive decrease in PCa and Ca2+ influx both in the period of GLU application and after its termination. These findings give new evidence in favour of the hypothesis that the GLU-induced Ca2+ overload of the neuron mainly from an impairment of its Ca2+ extrusion systems.
authors.affiliation: Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, Moscow, Russia. rans@rans.msk.ru
authors.forename: B I
authors.initials: BI
authors.lastname: Khodorov
authors.forename: D A
authors.initials: DA
authors.lastname: Fayuk
authors.forename: S G
authors.initials: SG
authors.lastname: Koshelev
authors.forename: O V
authors.initials: OV
authors.lastname: Vergun
authors.forename: V G
authors.initials: VG
authors.lastname: Pinelis
authors.forename: N P
authors.initials: NP
authors.lastname: Vinskaya
authors.forename: T P
authors.initials: TP
authors.lastname: Storozhevykh
authors.forename: E N
authors.initials: EN
authors.lastname: Arsenyeva
authors.forename: L G
authors.initials: LG
authors.lastname: Khaspekov
authors.forename: A P
authors.initials: AP
authors.lastname: Lyzhin
authors.forename: N
authors.initials: N
authors.lastname: Isaev
authors.forename: I V
authors.initials: IV
authors.lastname: Victorov
authors.forename: J M
authors.initials: JM
authors.lastname: Dubinsky
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D005453:Fluorescence; D018698:Glutamic Acid / Q000633:toxicity*; D007476:Ionophores / Q000494:pharmacology; D008345:Manganese; D016202:N-Methylaspartate / Q000633:toxicity; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009532:Nickel / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015220:Calcium Channels; D002614:Chelating Agents; D007476:Ionophores; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D018698:Glutamic Acid; D008345:Manganese; D004533:Egtazic Acid; D016202:N-Methylaspartate; D009532:Nickel; D002118:Calcium