ISSN:
1432-1912
Keywords:
4-Aminopyridine
;
GABA
;
Sympathetic ganglion
;
Presynaptic receptors
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Responses to bath-applications of 4-aminopyridine (4-AP) and γ-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 (0.1–0.3 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 (c) the presynaptic GABA-receptors revealed in this condition are similar to those on the postsynaptic membrane.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00504530
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