[Concentrations of free and bound 4-aminobutyric acid in human serum: reference values]

A rapid and sensitive procedure is described for the quantification of gamma-aminobutyric acid in human plasma, using ion-exchange fluorescence. Analytical values for gamma-aminobutyric acid vary according to the method of deproteinization, storage conditions and sample treatment. A practicable and precise method for the evaluation of free and bound gamma-aminobutyric acid is presented. The mean concentration of the free neurotransmitter in neurologically normal control subjects was 142.4 +/- 13.1 nmol/l (n = 30). The mean concentration of the bound form was 438.6 +/- 51.1 nmol/l in the same subgroup.