Transport of monoamine and amino acid neurotransmitters by primary astroglial cultures.
The transport of [3H]L-glutamate, [3H]L-aspartate, [3H] gamma-aminobutyric acid [( 3H]GABA), [3H]dopamine, [3H]norepinephrine and [3H]5-hydroxytryptamine (3H-5-HT) was measured in primary astroglial cultures from newborn rat cerebral hemispheres. There was a high-affinity uptake with a Km of 69.0 microM for L-glutamate, 12.3 microM for L-aspartate and 3.1 microM for GABA. The uptake showed properties of high capacity with a Vmax of 17.0 nmol X mg prot-1 X min-1 for L-glutamate, 1.1 nmol X mg prot-1 X min-1 for L-aspartate and 0.04 nmol X mg prot-1 X min-1 for GABA. No high-affinity high capacity transport system was found for the monoamines studied. Autoradiographic examination demonstrated a heavy deposit of grains suggesting a prominent accumulation of [3H]L-glutamate and [3H]L-aspartate in the astroglial-like cells of the cultures, while the [3H]GABA accumulation was less intense. On the other hand, there was only a weak accumulation of grains after incubating the cultures with [3H]dopamine, [3H]norepinephrine or [3H]5-HT. Thus, astroglial cells in culture accumulate amino acid neurotransmitters and monoamines in different ways with a high-affinity high-capacity uptake of glutamate, aspartate and GABA and a diffusion-uptake of dopamine, norepinephrine and 5-HT.
Hansson
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D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism*; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007700:Kinetics; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000596:Amino Acids; D005971:Glutamates; D018377:Neurotransmitter Agents; D001224:Aspartic Acid; D012701:Serotonin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D004298:Dopamine; D009638:Norepinephrine