GLUTAMATE-ACTIVATED IONIC CURRENTS IN CULTURED ASTROCYTES FROM TROUT - EVIDENCE FOR THE OCCURRENCE OF NON-N-METHYL-D-ASPARTATE RECEPTORS

Glutamate-induced currents were recorded from cultured trout astrocytes with the whole-cell variation of the patch-clamp technique. Ninety percent of the tested cells were directly depolarized by the amino acid neurotransmitter in a concentration-dependent manner, The depolarizing effect was due to an inward current that reversed near 0 mV and was accompanied by a noise increase, indicating the opening of an ion channel, Ion substitution experiments revealed that the glutamate-induced current was mainly carried by sodium ions but not chloride or calcium ions, The glutamate-induced response could be mimicked by the neuronal glutamate receptor subtype agonists kainate and quisqualate, while N-methyl-D-aspartate was without detectable effect. (c) 1995 Wiley-Liss, Inc.