Article date: 1979/8/1
PubMed ID: 226375
Journal name: European journal of pharmacology (ISSN: 0014-2999)
The release of 3H-GABA evoked by exposure to 30 mM potassium during 1 min was found to calcium independent in the rat occipital cortex and calcium dependent in the substantia nigra. Exposure to either muscimol 1 microM or GABA 1 microM inhibited the potassium-evoked release of 3H-GABA from the substantia nigra but not from the occipital cortex. The inhibitory effect of muscimol 1 microM on the potassium-evoked release of 3H-GABA from the substantia nigra was significantly antagonized by picrotoxin 10 microM. Exposure to either 10 or 100 microM pricrotoxin alone did not affect the potassium-evoked release of 3H-GABA. These results are compatible with the presence of a negative feedback mechanism in bagaergic nerve terminals of the rat substantia nigra which is mediated by presynaptic GABA autoreceptors. In addition, these results emphasize the importance of the calcium-dependent nature of the release of the neurotransmitter for demonstrating the modulation of transmitter release through presynaptic receptors.
Author List: Arbilla S, Kamal L, Langer S Z
Publication Types: Journal Article
Substances mentioned in the article: Receptors, Cell Surface; Picrotoxin; Muscimol; gamma-Aminobutyric Acid; Potassium; Calcium;
Mesh terms: Animals; Calcium/pharmacology; Cerebral Cortex/metabolism; In Vitro Techniques; Male; Muscimol/pharmacology; Nerve Endings/physiology; Picrotoxin/pharmacology; Potassium/pharmacology; Rats; Receptors, Cell Surface/physiology; Substantia Nigra/metabolism; gamma-Aminobutyric Acid/metabolism;