A new research program in directed toward understanding the function of sodium co-transport carriers that control the extracellular concentrations of major neurotransmitters in the mammalian brain. Experiments will identify GABA and glutamate transporters that play essential roles in synaptic transmission. Methods in molecular biology and electrophysiology will be combined to provide a structural and functional analysis. Specific experiments will: 1) Examine the electrophysiological properties of the gene products expressed by GABA transporters isolated from the rat brain and expressed in stable cell lines. The electrophysiology of the transporters will be compared. 2) Clone the cDNA of a GABA transporter expressed in horizontal cells of the catfish retina. Compare the electrophysiology of the native transporter expressed in horizontal cells and the single protein expressed in a stable cell line. 3) Clone the cDNA of a glutamate transporter expressed in Muller glial cells of the salamander retina. Compare the electrophysiology of the native transporter expressed in Muller glial cells and the single protein expressed in a stable cell line.