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Dose‐Dependent, K+‐Stimulated Efflux of Endogenous Taurine from Primary Astrocyte Cultures Is Ca2+‐Dependent
Journal article   Peer reviewed

Dose‐Dependent, K+‐Stimulated Efflux of Endogenous Taurine from Primary Astrocyte Cultures Is Ca2+‐Dependent

Robert A Philibert, Keith L Rogers, Albert J Allen and Gary R Dutton
Journal of neurochemistry, Vol.51(1), pp.122-126
07/1988
DOI: 10.1111/j.1471-4159.1988.tb04844.x
PMID: 2898000

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Abstract

The K+‐stimulated efflux of endogenous taurine from primary rat cerebellar astrocyte cultures prepared from 7–9‐day‐old rats was studied at 16–18 days in vitro using HPLC analysis. Taurine efflux was dose‐dependent at K+ concentrations between 10 mM and 80 mM, with an EC50 of approximately 50 mM. Maximum stimulation of efflux above basal levels ranged from 56% at 10 mM K+ (204 pmol/min/mg protein) to 470% at 80 mM K+ (960 pmol/min/mg protein). Removal of Ca2+ from the buffer and the addition of either 1 mM EGTA or 10 mM Mg2+ abolished K.+‐stimulated efflux. Taurine efflux peaked and fell in parallel with the K+ concentration, but with an approximate lag of 3–5 min. The time course and amount of preloaded [3H]taurine released did not differ significantly from that seen for endogenous efflux. Basal taurine efflux varied inversely with the extracellular concentration of Ca2+ over the concentration range 0–5.0 mM. The observed Ca2+ dependence is consistent with a role for Ca2+ in the regulation of taurine release. Furthermore, taurine release from astrocytes in response to elevated K+ may reflect a neuromodulatory role for this amino acid in the CNS.
 Ca2+ dependence Taurine efflux Astrocytes K+ stimulation

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