The release of (3H)-GABA from the rabbit retina

The neuronal and glial release of (3H)-GABA from rabbit retina has been studied. The results indicate, that neither are there any glutamate, aspartate or glycine receptors on the GABA accumulating neurons, nor any GABA autoreceptors. (3H)-GABA was found to be released by 40 mM K+ from retinal neurons, but not from glia, and the release was not dependent on extracellular Ca++. This indicates a release from a non vesicular transmitter pool. Ouabain has been proposed as a pharmacological tool for studying the release of (3H)-GABA located in neuronal cytoplasm. However, it induced an increased release of (3H)-GABA from both neurons and glia and it is therefore unlikely that it can be used for the specific purpose of studying release from neuronal cytoplasm.