Effects of anion channel blockers on hyposmotically induced amino acid release from the in vivo rat cerebral cortex.
A cortical cup model with continuous perfusion of artificial cerebrospinal fluid (containing 134 mM NaCl) was used to investigate the effects of anion channel blockers on the hyposmotically-induced release of amino acids from the in vivo rat cerebral cortex. The hyposmotic stimulus (25 mM NaCl) evoked a release of taurine, glutamate, aspartate, glycine, phosphoethanolamine and GABA. Topically applied anion channel blockers 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (1 mM); 4-acetamido-4'-isothiocyanatostilbene-2,2-disulfonic acid (2 mM); 5-nitro-2-(3-phenylpropylamino) benzoic acid (350 microM); niflumic acid (500 microM); tamoxifen (20 microM) and arachidonic acid (0.5 microM) all significantly reduced the hyposmotically-induced release of taurine. The releases of glutamate, aspartate, glycine, phosphoethanolamine and GABA were variably susceptible to inhibition by these compounds. These results demonstrate that osmoregulatory processes in cortical cells, in vivo, involve amino acids, with taurine playing a dominant role. The efflux of taurine and, to a lesser extent, the other amino acids may be mediated by anion channels.
Estevez
A Y
AY
Department of Physiology, School of Medicine, Wayne State University, Detroit MI 48201, USA.
O'Regan
M H
MH
Song
D
D
Phillis
J W
JW
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000838:Anions; D001224:Aspartic Acid / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D004983:Ethanolamines / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007038:Hypotonic Solutions; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000502:physiology; D008297:Male; D009544:Niflumic Acid / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride; D013629:Tamoxifen / Q000494:pharmacology; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000596:Amino Acids; D000838:Anions; D004983:Ethanolamines; D007038:Hypotonic Solutions; D007473:Ion Channels; D013629:Tamoxifen; D013654:Taurine; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D001224:Aspartic Acid; D018698:Glutamic Acid; D012965:Sodium Chloride; D009544:Niflumic Acid; D005680:gamma-Aminobutyric Acid; C005448:phosphorylethanolamine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D005998:Glycine