Ion dependency of uptake and release of GABA and (RS)-nipecotic acid studied in cultured mouse brain cortex neurons

✍ Scribed by O. M. Larsson; J. Drejer; L. Hertz; Dr. A. Schousboe

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 737 KB
• Volume: 9
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490090306

✦ Synopsis

The influence of sodium ions on GABA uptake into neurons cultured from cerebral cortex was investigated at sodium concentrations ranging from 16 to 15 1 mh4. Sodium did not affect the K, for GABA uptake but the uptake rates as a function of the sodium concentration was sigmoid at all GABA concentrations studied (1-200 FM). Hill plots of these curves exhibited straight lines with slopes of 1.7-2.1, suggesting that the coupling ratio between sodium and GABA is at least 2. (RS)-Nipecotic acid, a GABA analogue, was transported with high affinity (K, 8.0 * 2.1 bM) like GABA, but the V,,, for nipecotic acid was lower than found for GABA (0.664 2 0.035 versus 0.955 2 0.059 nmol X min-' X mg-I), suggesting a microheterogeneity of the GABA transport sites. Neurons loaded with the respective vitiated compounds exhibited a pronounced K + -stimulated, calcium-dependent release of both GABA and nipecotic acid indicating that these cultured cells have developed functionally active GABAergic synapses.