Glutamate and kainate increase intracellular sodium activity in leech neuropile glial cells.
Na+-selective, double-barrelled microelectrodes were used to measure intracellular Na+ activity (aiNa) and membrane potential (Em) in neuropile glial cells of isolated segmental ganglia in the leech Hirudo medicinalis. Bath application of glutamate (10(-3) M) resulted in membrane depolarizations of about 5 mV and a concomitant increase of aiNa by between 2 and 10 mM. Kainate (10(-4) M) elicited depolarizations of up to 40 mV amplitude followed by a prominent after hyperpolarization. During kainate, aiNa increased by 7 to 25 mM. In contrast to glutamate, an initial decrease of aiNa was detected during the action of kainate. N-methyl-D-aspartate (NMDA, 10(-5)-10(-3) M) had no effect of Em and aiNa. The results indicate that leech glial cells have a kainate-preferring non-NMDA glutamate receptor.
Ballanyi
K
K
Physiologisches Institut, Zentrum Physiologie und Pathophysiologie, Georg-August-Universität, Göttingen, Federal Republic of Germany.
Dörner
R
R
Schlue
W R
WR
D000818:Animals; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology*; D007865:Leeches / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000502:physiology*
D005971:Glutamates; D018698:Glutamic Acid; D012964:Sodium; D007608:Kainic Acid