PRESYNAPTIC ACTIONS OF β‐AMINOBUTYRIC ACID AND SOME ANTAGONISTS IN A SLICE PREPARATION OF CUNEATE NUCLEUS

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Abstract
1 A slice preparation of the rat cuneate nucleus is described which is suitable for electrophysiological studies on the presynaptic action of drugs. 2 Superfusion of a slice with γ-aminobutyric acid (GABA) depolarized the afferent nerves in a concentration-related manner. The responses were CI “-dependent. Depolarizations to high concentrations of GABA often faded. Glycine and l-glutamate had little effect. 3 (-h)-Bicuculline antagonized GABA in an apparently competitive manner (pA2 = 5.35) at low response levels. Strychnine was 10 times less potent. Responses to high concentrations of GABA were sometimes potentiated by (+)-biculline and strychnine. 4 Bemegride and leptazol both antagonized GABA, but with low potency and in a manner which was clearly not competitive.