L-glutamate-stimulated taurine release from rat cerebral cultured astrocytes.
We characterized L-glutamate-stimulated taurine release from cultured astrocytes prepared from rat cerebrum. L-glutamate (0.5 mM) stimulated release of 3H-labeled and endogenous taurine, where the rate of release reached maximum in 40 min. L-glutamate increased astrocytic volume [3H-O-methyl-D-glucose (3H-OMG) space] with a similar time course to 3H-taurine release. Quisqualate, L-aspartate, DL-homocysteate, and L-cysteate increased both astrocytic 3H-OMG space and 3H-taurine release from cultured astrocytes, while kainate (1 mM) stimulated 3H-taurine release without affecting astrocytic volume. N-methyl-D-aspartate had no effect on 3H-taurine release and astrocytic volume. Treatment of astrocytes with dibutyryl cAMP reduced the effect of kainate on 3H-taurine release. L-glutamate-stimulated 3H-taurine release was attenuated by removal of extracellular Cl- and in hyperosmotic medium, which prevented L-glutamate-induced increase in 3H-OMG space of cultured astrocytes. These results indicate that L-glutamate stimulates taurine release from astrocytes through swelling-triggered mechanisms and that kainate causes the release through volume-independent mechanisms.
Koyama
Y
Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Suita, Japan.
Ishibashi
T
T
Tanaka
K
K
Baba
A
A
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D005971:Glutamates / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013654:Taurine / Q000378:metabolism*
D002712:Chlorides; D005971:Glutamates; D013654:Taurine; D003994:Bucladesine