Pentobarbitone slows the dissociation of GABA from rat brain synaptosomal binding sites

The dissociation of GABA from rat brain synaptosomal binding sites is characterized by an initial rapid phase followed by a slower phase which may represent dissociation of GABA from high affinity binding sites. The dissociation rate constant (K-1) calculated from this secondary phase is significantly reduced by pentobarbitone (100 micrometers). This result supports the finding that barbiturates increase the affinity of GABA for a high affinity binding site.