Na super(+)-mediated coupling between AMPA receptors and K sub(Na) channels shapes synaptic transmission

Na super(+)-activated K super(+) (K sub(Na)) channels are expressed in neurons and are activated by Na super(+) influx through voltage-dependent channels or ionotropic receptors, yet their function remains unclear. Here we show that K sub(Na) channels are associated with AMPA receptors and that their activation depresses synaptic responses. Synaptic activation of K sub(Na) channels by Na super(+) transients via AMPA receptors shapes the decay of AMPA-mediated current as well as the amplitude of the synaptic potential. Thus, the coupling between K sub(Na) channels and AMPA receptors by synaptically induced Na super(+) transients represents an inherent negative feedback mechanism that scales down the magnitude of excitatory synaptic responses.