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Hyperpolarization induces a rise in intracellular sodium concentration in dopamine cells of the substantia nigra pars compacta
Author(s) -
Knöpfel T.,
Guatteo E.,
Bernardi G.,
Mercuri N. B.
Publication year - 1998
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1998.00195.x
Subject(s) - substantia nigra , pars compacta , dopamine , neuroscience , hyperpolarization (physics) , intracellular , chemistry , microbiology and biotechnology , biology , dopaminergic , stereochemistry , nuclear magnetic resonance spectroscopy
Summary We investigated the effect of changes in membrane‐voltage on intracellular sodium concentration ([Na + ] i ) of dopamine‐sensitive neurons of the substantia nigra pars compacta in a slice preparation of rat mesencephalon. Whole‐cell patch‐clamp techniques were combined with microfluorometric measurements of [Na + ] i using the Na + ‐sensitive probe, sodium‐binding benzofuran isophthalate (SBFI). Hyperpolarization of spontaneously active dopamine neurons (recorded in current‐clamp mode) caused the cessation of action potential firing accompanied by an elevation in [Na + ] i . In dopamine neurons voltage‐clamped at a holding potential of −60 mV elevations of [Na + ] i were induced by long‐lasting (45–60 s) voltage jumps to more negative membrane potentials (–90 to −120 mV) but not by corresponding voltage jumps to −30 mV. These hyperpolarization‐induced elevations of [Na + ] i were depressed during inhibition of I h , a hyperpolarization‐activated inward current, by Cs + . Hyperpolarization‐induced elevations in [Na + ] i might occur also in other cell types which express a powerful I h and might signal lack of postsynaptic activity.