1244891

Presynaptic actions of 4-aminopyridine and gamma-aminobutyric acid on rat sympathetic ganglia in vitro.

Article date: 1980/11/1

PubMed ID: 1244891

Journal name: Naunyn-Schmiedeberg's archives of pharmacology (ISSN: 0028-1298)

ABSTRACT

Responses to bath-applications of 4-aminopyridine(4-AP) and gamma-aminobutyric acid (GABA) were recorded intracellularly from neurones in the rat isolated superior cervical ganglion. 4-aminopyridine (0.1-1.0 mmol/l) usually induced spontaneous action potentials and excitatory postsynaptic potentials (EPSPs), which were blocked by hexamethonium. Membrane potential was unchanged; spike duration was slightly increased. Vagus nerve B- and C-fibre potentials were prolonged. In 4-AP solution (0.2-0.3 mmol/l), GABA (0.1 mmol/l), 3-aminopropanesulphonic acid or muscimol evoked “bursts” of spikes and EPSPs in addition to a neuronal depolarization. These “bursts”, which were not elicited by glycine, glutamate, taurine or (+/-)-baclofen, were completely antagonised by hexamethonium, tetrodotoxin or bicuculline methochloride. It is concluded that: (a) 4-AP has a potent presynaptic action on sympathetic ganglia; (b) presynaptic actions of GABA can be recorded postsynaptically in the presence of 4-AP; and © the presynaptic GABA-receptors revealed in this condition are similar to those on the postsynaptic membrane.

Author List: Galvan M, Grafe P, ten Bruggencate G

Publication Types: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Substances mentioned in the article: Aminopyridines; Receptors, Cell Surface; gamma-Aminobutyric Acid; Bicuculline;

Mesh terms: Action Potentials/drug effects; Aminopyridines/pharmacology; Animals; Bicuculline/pharmacology; Female; Ganglia, Sympathetic/drug effects; In Vitro Techniques; Male; Membrane Potentials/drug effects; Rats; Receptors, Cell Surface; gamma-Aminobutyric Acid/metabolism;

Citations: - 314974

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