Effects of Sodium and Bicarbonate Ions on ?-Aminobutyric Acid Receptor Binding in Synaptic Membranes of Rat Brain

Publisher Website
Google Scholar
Abstract
Crude synaptic membranes treated with Triton X-100 (TX) bound GABA to 2 classes of receptor sites in Na+-free 10 mM-Tris-sulfate buffer (pH 7.4), but to only a single class of receptor sites in 10 mM Tris-sulfate buffer (pH 7.4) containing 150 mM-NaCl. The high-affinity receptor site in TX membranes was specifically masked in the presence of Na+. TX membranes incubated in Krebs-Ringer bicarbonate solution (pH 7.4) bound GABA to 2 classes of receptor sites despite the presence of Na+. Addition of HCO3- to the Na+-containing 10 mM-Tris-sulfate buffer (pH 7.4) could evidently restore the high-affinity class of GABA receptors, rendering both classes detectable. Na+ and HCO3- may have a regulatory function on GABA binding to the receptor.