Kinetic differences in GABA receptor binding following GABA and bicuculline methiodide pretreatment

The kinetics of [3H]GABA binding were studied in cortical membranes following GABA and bicuculline methiodide (BCM) pretreatment at 37 degrees C. The slower parts of the biphasic ON and OFF rates can be attributed to the high affinity sites. BCM pretreatment decreased the ON and OFF rates of [3H]GABA binding, including the rapid initial ON- and OFF-phases. Decreased association rates of GABA were independent of GABA and concentration and suggested a rate determining dissociation of bound BCM (t1/2 = 35 min).