Binding experiment k_d values and physiologically active gaba concentrations: An only apparent contradiction?

Abstract

An apparent contradiction exists between GABA_A receptor binding K_d's (<10⁻⁶M) and GABA concentrations physiologically active in various systems (>10⁻⁶M). Taking in account that synaptic cleft GABA action and removal should be rather quick (within 2 ms) we show that in principle there is no contradiction between low K_D values (100-150 nM) and high physiologically active GABA concentrations (>40 μM).