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INFLUENCE OF CELLULAR TRANSPORT ON THE INTERACTION OF AMINO ACIDS WITH γ‐AMINOBUTYRIC ACID (GABA)‐RECEPTORS IN THE ISOLATED OLFACTORY CORTEX OF THE GUINEA‐PIG
Author(s) -
BROWN D.A.,
COLLINS G.G.S.,
GALVAN M.
Publication year - 1980
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1980.tb10414.x
Subject(s) - receptor , neuroscience , olfactory system , guinea pig , gamma aminobutyric acid , aminobutyric acid , amino acid , biology , chemistry , microbiology and biotechnology , biochemistry , biophysics , endocrinology
1 Freshly cut guinea‐pig olfactory cortex slices contained 2.2 mmol γ‐aminobutyric acid (GABA)/kg tissue weight. This declined during in vitro incubation at 25°C in the absence of exogenous GABA, but increased to 6.95 mmol/kg after 1.5 h incubation in 1 m m GABA. 2 Uptake of [ 3 H]‐GABA (1 μ m ) was inhibited by 1 m m (±)‐nipecotic acid (−83%), β‐amino‐ n ‐butyric acid (BABA) (−59%), l ‐2,4‐diaminobutyric acid (DABA) (−63%), (±) cis ‐3‐aminocyclohexane carboxylic acid (ACHC) (−53%), and 3‐aminopropanesulphonic acid (3‐APS) (−26%), but was increased by β‐alanine (BALA) (+23%). 3 Autoradiographs showed steep concentration gradients of radioactivity across slices incubated for short periods in [ 3 H]‐GABA. 4 Efflux of [ 3 H]‐GABA from pre‐loaded slices was accelerated strongly by nipecotic acid, BABA, DABA and ACHC but weakly or not all by BALA or 3‐APS. 5 Nipecotic acid (1 m m ) potentiated the surface‐depolarization of the slice produced by GABA but not that produced by 3‐APS. 6 The depolarizing actions of DABA, BABA, nipecotic acid and ACHC, but not that of 3‐APS or BALA, were potentiated when the endogenous GABA content of slices was raised. 7 It is concluded that: (a) the depolarizing action of exogenous GABA is limited by cellular uptake; (b) surface‐depolarizations produced by nipecotic acid, DABA, BABA and ACHC may be mediated by the release of GABA; and (c) neuronal, rather than glial, transport systems are responsible for these effects.