Bidirectional Movement of γ‐Aminobutyric Acid in Rat Spinal Cord Slices

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Abstract
The bidirectional movement of GABA was studied in slices of rat spinal cord which were incubated in small volumes of medium. The appearance in the medium of endogenous GABA and the disppearance from the medium of [14C]GABA were used to calculate the rates of unidirectional uptake and unidirectional release of GABA. Under these conditions no net uptake of GABA was observed when slices were incubated in media containing concentrations of GABA as high as 25 .mu.M. Elevated K (60 mM) stimulated the unidirectional release of endogenous GABA from spinal cord slices by a Ca-dependent process. Ouabain (0.1 mM) more than doubled the unidirectional release of endogenous GABA in a Ca-independent manner; unidirectional uptake was inhibited by 44%. Nipecotic acid (1.0 mM) stimulated unidirectional release and inhibited unidirectional uptake of GABA.