Fig. 16.
Multiple conductance levels of AMPA receptors. Upper panel: Schematic of slow NBQX unbinding from an AMPA receptor, which allows the time course of channel activation by glutamate to be observed. Lower panel: Response from a single GluA1 + γ-2 (tandem) receptor in an outside-out patch that has NBQX bound to all subunits after rapid exchange into a solution lacking NBQX and containing 10 mM glutamate (VHOLD −60 mV). Each of four antagonist unbinding events is evident as glutamate occupies the available site following NBQX dissociation, which enables the opening to an individual sublevel, with chord conductance given (in pS). Reproduced with permission from Coombs et al. (2017).