Localization and pharmacological characterization of voltage dependent calcium channels in cultured neocortical neurons

The physiological significance and subcellular distribution of voltage dependent calcium channels was defined using calcium channel blockers to inhibit potassium induced rises in cytosolic calcium concentration in cultured mouse neocortical neurons. The cytosolic calcium concentration was measured u...

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Bibliographic Details
Published in:International journal of developmental neuroscience 2001-02, Vol.19 (1), p.1-10
Main Authors: Timmermann, Daniel B., Lund, Trine M., Belhage, Bo, Schousboe, Arne
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Action Potentials - physiology
Animals
Calcium - metabolism
Calcium Channel Blockers - pharmacology
Calcium Channels - drug effects
Calcium Channels - metabolism
Carrier Proteins - drug effects
Carrier Proteins - metabolism
Cells, Cultured - cytology
Cells, Cultured - drug effects
Cells, Cultured - metabolism
Chelating Agents - pharmacology
Cytosol - drug effects
Cytosol - metabolism
Female
Fetus
Fura-2 - pharmacokinetics
GABA Agonists - pharmacology
GABA Plasma Membrane Transport Proteins
gamma-Aminobutyric Acid - metabolism
Membrane Proteins - drug effects
Membrane Proteins - metabolism
Membrane Transport Proteins
Mice
Neocortex - cytology
Neocortex - drug effects
Neocortex - metabolism
Neurons - cytology
Neurons - drug effects
Neurons - metabolism
Nipecotic Acids - pharmacology
Organic Anion Transporters
Potassium - metabolism
Potassium - pharmacology
Presynaptic Terminals - drug effects
Presynaptic Terminals - metabolism
Sodium Channels - drug effects
Sodium Channels - metabolism
Synaptic Vesicles - drug effects
Synaptic Vesicles - metabolism
Tetrodotoxin - pharmacology
Tiagabine
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Summary:The physiological significance and subcellular distribution of voltage dependent calcium channels was defined using calcium channel blockers to inhibit potassium induced rises in cytosolic calcium concentration in cultured mouse neocortical neurons. The cytosolic calcium concentration was measured using the fluorescent calcium chelator fura‐2. The types of calcium channels present at the synaptic terminal were determined by the inhibitory action of calcium channel blockers on potassium‐induced [3H]GABA release in the same cell preparation. L‐, N‐, P‐, Q‐ and R‐/T‐type voltage dependent calcium channels were differentially distributed in somata, neurites and nerve terminals. ω‐conotoxin MVIIC (ω‐CgTx MVIIC) inhibited approximately 40% of the Ca2+‐rise in both somata and neurites and 60% of the potassium induced [3H]GABA release, indicating that the Q‐type channel is the quantitatively most important voltage dependent calcium channel in all parts of the neuron. After treatment with thapsigargin the increase in cytosolic calcium was halved, indicating that calcium release from thapsigargin sensitive intracellular calcium stores is an important component of the potassium induced rise in cytosolic calcium concentration. The results of this investigation demonstrate that pharmacologically distinct types of voltage dependent calcium channels are differentially localized in cell bodies, neurites and nerve terminals of mouse cortical neurons but that the Q‐type calcium channel appears to predominate in all compartments.
ISSN:0736-5748
1873-474X
DOI:10.1016/S0736-5748(00)00091-5