Article date: 1990/8/21
PubMed ID: 1699768
Journal name: European journal of pharmacology (ISSN: 0014-2999)
The effects of gamma-aminobutyric acid (GABA) on the glutamate receptor chloride ion (Cl-) channel complex were examined in mechanically isolated and internally perfused Aplysia neurons using a concentration clamp technique. GABA at concentrations of 3 x 10(-6) M or more, concentration dependently delayed the recovery of the glutamate response from desensitization. This effect was independent of the GABA response and Cl- redistribution. Muscimol (10(-4) M) mimicked the effect of GABA. However, this was not the case for baclofen (10(-3) M). In some isolated neurons, GABA at concentrations of more than 10(-4) M clearly induced an additional Cl- current, the current kinetics of which were different from those induced by lower concentrations of GABA. Even in the continued presence of 10(-4) M GABA, which desensitized the fast GABA response, higher concentrations of GABA (3 x 10(-4) M to 10(-2) M) elicited the additional current in a concentration-dependent manner. The presence of 10(-4) M glutamate completely abolished this current, indicating cross-desensitization between the glutamate and slow GABA responses. High concentrations of GABA (3 x 10(-2) M) did not activate the glutamate receptor coupled to the large cation channel. The results suggest that, in Aplysia neurons, the glutamate receptor-Cl- channel complex has some similarities to the GABA receptor-Cl- channel complex.
Author List: Oyama Y, Ikemoto Y, Kits K S, Akaike N
Publication Types: Journal Article; Research Support, Non-U.S. Gov't
Substances mentioned in the article: Chlorides; Ion Channels; Receptors, Glutamate; Receptors, Neurotransmitter; Muscimol; gamma-Aminobutyric Acid; Baclofen;
Mesh terms: Animals; Anura; Aplysia/metabolism; Baclofen/pharmacology; Chlorides/metabolism; In Vitro Techniques; Ion Channels/drug effects; Muscimol/pharmacology; Neurons/drug effects; Perfusion; Receptors, Glutamate; Receptors, Neurotransmitter/drug effects; gamma-Aminobutyric Acid/pharmacology;