ON THE ACTIVITY OF GAMMA-AMINOBUTYRIC-ACID AND GLUTAMATE TRANSPORTERS IN CHICK EMBRYONIC NEURONS AND RAT SYNAPTOSOMES

The uptake of radioactive gamma-aminobutyric acid (GABA) and D-asparate and the effect of SKF 89976-A, a non-substrate inhibitor of the GABA transporter, on this uptake have been investigated. Neuronal cultures from eight-day-old chick embryos grown for three or six days in vitro, were used as a model. For comparison, we also used the P2-fraction from rat. Neuronal cultures grown for three and six days expressed high-affinity uptake systems for [H-3]GABA and for D-[H-3]aspartate with an increasing V(max) during this period. The lipophilic non-substrate GABA uptake inhibitor, SKF 89976-A, inhibited transporter mediated uptake of GABA both in cell cultures from chicken, and in P2-fractions from rat. The results also showed that SKF 89976-A was a poor inhibitor of the uptake of D-aspartate. We found no non-saturable uptake of D-aspartate.