Chloride ions preferentially mask high-affinity GABA binding sites.

Chloride ions (Cl-) act to regulate the appearance of gamma-aminobutyric acid (GABA) binding sites in synaptic membranes from bovine retinas. Scatchard analysis indicates that the presence of Cl- results in a preferential decrease (85%) in the number of high-affinity binding sites, with no statistically significant change in the affinity (KD) of either the high- or low-affinity sites. The finding that the appearance of this binding site is altered by the presence of Cl- may indicate that Cl- acts, either directly or indirectly, to regulate the appearance, and hence function, of the high-affinity GABA receptor.