Stereospecificity of 2,4-diaminobutyric acid with respect to inhibition of 4-aminobutyric acid uptake and binding.

S(+)-2,4-Diaminobutyric acid is at least 20 times more potent than the R(-) stereoisomer as an inhibitor of the sodium-dependent uptake of 4-aminobutyric acid (GABA) in rat brain slices. Both isomers, however, are equipotent as inhibitors of sodium-independent binding of GABA to membranes from rat brain. The latter finding may be relevant to the reported neurotoxicity in rats of both isomers of 2,4-diaminobutyric acid after intracisternal injection.