title: Changes in cytosolic glucose level in ATP stimulated live astrocytes.
abstract: Astrocytes which lie between brain capillaries and neuronal terminals are the primary site of glucose uptake and have a key role in coupling synaptic activity to glucose utilization in the central nervous system (CNS). We used a fluorescence resonance energy transfer (FRET) based approach to monitor cytosolic glucose in astrocytes. We determined the effect of increasing extracellular glucose concentrations on FRET ratio as a measure of increased cytosolic glucose in astrocytes. By briefly raising extracellular glucose concentration, astrocytes responded promptly by increased cytosolic glucose levels, which was manifested by decreased time-dependent FRET ratio. The FRET ratio fall-time recorded at low extracellular D-glucose concentration change (from 0 to 0.5 mM) was 53 s, whereas 17 s was recorded by raising extracellular concentration of D-glucose from 0 to 10 mM, which is likely due to facilitated d-glucose entry along the increased D-glucose gradient across the plasmalemma. The relationship between the extracellular glucose concentration and the FRET ratio change is limited to the maximal ratio change, where the D-glucose plasma membrane permeability is balanced by the cytosolic utilization. We measured the effect of extracellular ATP, an important extracellular messenger for astrocyte-to-astrocyte communication, on intracellular glucose concentration. The results show that stimulation of astrocytes with ATP (1 mM) decreases cytosolic glucose concentration with a time constant of ∼145 s. The mechanism of this change is discussed.
authors.affiliation: Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, Slovenia.
authors.forename: Mateja
authors.initials: M
authors.lastname: Prebil
authors.forename: Helena H
authors.initials: HH
authors.lastname: Chowdhury
authors.forename: Robert
authors.initials: R
authors.lastname: Zorec
authors.forename: Marko
authors.initials: M
authors.lastname: Kreft
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D005947:Glucose / Q000032:analysis / Q000378:metabolism*; D051381:Rats
chemical_list: D000255:Adenosine Triphosphate; D005947:Glucose