Kinetic characterization of inhibition of gamma-aminobutyric acid uptake into cultured neurons and astrocytes by 4,4-diphenyl-3-butenyl derivatives of nipecotic acid and guvacine.

The effects of N-(4,4-diphenyl-3-butenyl) derivatives of nipecotic acid (SKF-89976-A and SKF-100844-A) and guvacine (SKF-100330-A) on neuronal and astroglial gamma-aminobutyric acid (GABA) uptake were investigated. In addition, the uptake of SKF-89976-A was studied using the tritiated compound. All of the compounds were found to be competitive inhibitors of GABA uptake irrespective of the cell type, with Ki values similar to or lower than those of the parent amino acids. Moreover, none of the compounds exhibited selectivity with regard to inhibition of neuronal and glial GABA uptake. In spite of the competitive nature of SKF-89976-A, the compound was not transported by the GABA carriers in the two cell types, because no saturable uptake could be demonstrated.