Mitochondrial polarization in rat hippocampal astrocytes is resistant to cytosolic Ca(2+) loads

Détails

ID Serval
serval:BIB_44BF3D8645D7
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Mitochondrial polarization in rat hippocampal astrocytes is resistant to cytosolic Ca(2+) loads
Périodique
Journal of Neuroscience Research
Auteur(s)
Kahlert  S., Schild  L., Reiser  G.
ISSN
0360-4012 (Print)
Statut éditorial
Publié
Date de publication
12/2001
Volume
66
Numéro
5
Pages
1019-27
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Dec 1
Résumé
The influence of physiological Ca(2+)-inducing stimuli and agents mimicking ischemic conditions on mitochondrial potential was studied in postnatal (P1) hippocampal astrocytes. Cytosolic Ca(2+) loads with characteristic kinetics of rise and duration, detected by Fura-2, were provoked by extracellular Ca(2+) influx, release from InsP(3)-sensitive intracellular stores, or inhibition of the reloading of endoplasmic reticulum Ca(2+) stores. Inhibitors of mitochondrial respiration caused only moderate release of Ca(2+) from intracellular stores, inducing a rise of less than 60 nM. The maximal Ca(2+) rise was found with InsP(3)-mediated responses (500 nM; via ATP) or with ionophore (4-Br-A23187)-mediated Ca(2+) influx from extracellular medium (770 nM). Remarkably, all these agents causing significant rise of cytosolic Ca(2+), only minimally depolarized the mitochondria. Membrane potential of mitochondria was monitored by Rh123 or TMRE. Depolarization was only found with very high cytosolic Ca(2+) levels (above 60 microM; measured by fura FF). These were achieved with external Ca(2+) influx by ionophore in combination with inhibition of glycolysis. Thus, mitochondria in the astrocytes are obviously not sensitive to moderate cytosolic Ca(2+) loads, irrespective of the source of Ca(2+). Furthermore, isolated rat brain mitochondria display a low sensitivity of respiratory activity to Ca(2+), which is consistent with the data obtained with the astrocytes in vitro. The capacity of isolated mitochondria to build up a potential was gradually reduced at low micromolar Ca(2+) and totally compromised only at Ca(2+) concentrations in the 100 microM range.
Mots-clé
Adenosine Triphosphate/metabolism Animals Animals, Newborn Astrocytes/drug effects/*metabolism Brain Ischemia/*metabolism/physiopathology Calcium/*metabolism Cells, Cultured Cytochrome c Group/metabolism/pharmacology Cytosol/drug effects/*metabolism Energy Metabolism/drug effects/*physiology Enzyme Inhibitors/pharmacology Fluorescent Dyes/diagnostic use Glycolysis/drug effects/physiology Hippocampus/drug effects/*metabolism/physiopathology Intracellular Membranes/drug effects/metabolism Ionophores/pharmacology Membrane Potentials/drug effects/physiology Membrane Transport Proteins/drug effects/physiology Mitochondria/drug effects/*metabolism Oxidative Phosphorylation/drug effects Rats Rats, Wistar
Pubmed
Web of science
Création de la notice
24/01/2008 13:55
Dernière modification de la notice
20/08/2019 14:49
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