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Weak organic acids induce taurine release through an osmotic‐sensitive process in in vivo rat hippocampus
Author(s) -
Solis J. M.,
Herranz A. S.,
Herreras O.,
Menéndez N.,
del Rio R. Martin
Publication year - 1990
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490260205
Subject(s) - taurine , extracellular , chemistry , sodium , propionate , sodium propionate , biochemistry , nigericin , bicarbonate , osmolyte , microdialysis , sodium pyruvate , in vivo , biophysics , amino acid , biology , membrane , organic chemistry , microbiology and biotechnology
Isotonic media containing sodium salts from weak organic acids induce cell swelling in several experimental preparations (Grinstein et al., 1984; Jakubovicz et al., 1987). In vivo perfusion of rat dentate gyrus, using a microdialysis probe, with modified Krebs‐Ringer bicarbonate solutions in which 50 mM NaCl was isotonically substituted by the sodium salts from organic acids with a p K a value of >2 (acetate, propionate, or pyruvate), induced a reversible increase in the extracellular taurine concentration. By contrast, similar NaCl substitutions with sodium salts from the stronger organic acids isethionate and methanesulfonate did not change extracellular taurine levels. Extracellular taurine increases evoked by acetate, propionate, or pyruvate were almost completely abolished when the perfusion liquid was made hypertonic by adding sucrose (50 mM). A 30% reduction of the acetate‐induced extracellular taurine increase was observed both when amiloride was present or when the [Na + ] 0 was lowered. Both conditions are known to inhibit Na + /H + exchange. These results are compatible with the hypothesis that acid load‐induced taurine release is stimulated by an osmotic sensitive mechanism, part of which is dependent on activation of the Na + /H + exchange.