Chloride dependence of the K(+)-stimulated release of taurine from synaptosomes.
Exposure of a crude synaptosomal fraction to K+ concentrations ranging from 25 to 100 mM evokes the release of [3H]taurine and [3H]GABA. These high concentrations of K+ induce, besides depolarization, a marked synaptosomal swelling, which is prevented by replacing chloride in the solutions with the largely impermeant anion gluconate. The depolarizing effect of K+ is unaffected by omission of chloride. The K(+)-evoked release of taurine seems related to K(+)-induced changes in synaptosomal volume rather than to a depolarizing effect, since it is totally calcium-independent but is abolished by reducing chloride and by making solutions hypertonic with mannitol. The release of [3H]GABA, in contrast is unaffected in chloride-free or hypertonic solutions.
Sánchez Olea
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R
Institute of Cellular Physiology, National University of Mexico, Mexico City.
Pasantes-Morales
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H
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology*; D006982:Hypertonic Solutions; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013654:Taurine / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D002712:Chlorides; D006982:Hypertonic Solutions; D002034:Bumetanide; D013654:Taurine; D001464:Barium; D005680:gamma-Aminobutyric Acid; D011188:Potassium