Potassium permeability of voltage-operated calcium channels of dorsal root ganglion neurons in a calcium-free medium |
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Authors: | S V Korol’ T Yu Korol’ E P Kostyuk P G Kostyuk |
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Institution: | (1) International Center for Molecular Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine;(2) Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine |
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Abstract: | In freshly isolated neurons of the rat spinal ganglia, we studied the behavior of voltage-operated calcium channels of these
cells under conditions of the absence of calcium ions in the extracellular solution; a patch-clamp technique in the whole-cell
configuration was used. We found that such channels in a part of the studied neurons lose their selectivity in a calcium-free
potassium-containing solution and become capable of passing an inward potassium current. This current was inhibited by blockers
of voltage-operated calcium channels, nifedipine and nickel, and also was to some extent inhibited by caffeine. The latter
effect is realized, perhaps, due to calcium-dependent inactivation of calcium channels induced by the action of calcium ions
released from the endoplasmic reticulum upon caffeine-induced activation of ryanodine receptors. The peculiarities of current-voltage
relationships and characteristics of activation/inactivation of calcium channels modified in calcium-free medium and the possible
mechanisms of such modification are discussed.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 93–99, March–April, 2008. |
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Keywords: | voltage-operated calcium channels calcium-free solution potassium current calcium-dependent inactivation nifedipine caffeine |
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