The amino acid GABA plays an important role in the processing of visual information in the vertebrate retina. Carrier-mediated transport of GABA by neurons and glia is one key element in the proper functioning of GABAergic pathways. It has long been suspected that neuronal and glial transport systems for GABA in the central nervous system are distinct and have differing properties. The purpose of the proposed project is to examine structural and functional differences between neuronal and glial GABA transporters in the retina. Electrophysiological techniques, including whole- cell and perforated patch recordings, will be used to examine the properties of GABA transport in enzymatically isolated horizontal (neural) and Muller (glial) cells of the skate retina. In addition, the GABA transporters of these cells are to be cloned and then expressed in oocytes; dual-electrode voltage-clamp and giant patch recordings from oocytes will be used to examine functional and pharmacological properties. These studies should clarify the role that neuronal and glial GABA transport mechanisms play in establishing and maintaining normal retinal function.
