Functional high- and low affinity agonist binding sites at native dorsal horn AMPA receptors

TRANSMISSION and dorsal horn (DH) of the spinal cord involves activation of AMPA-type glutamate receptors (AMPARs). We have studied the properties of native AMPARs in freshly dissociated laminae I-II neurones from postnatal r ats using a modified form of the concentration-clamp technique for fast ago nist application. Analysis of kainic acid dose-response curves showed the e xistence of two types of functional agonist binding sites governing AMPAR a ctivation. These sites differ by their affinity for the agonist. Depending on the neurotransmitter concentration reached in the synaptic cleft, the re lative contribution of high affinity and low affinity sites might play an i mportant role in the shaping of AMPAR-mediated postsynaptic currents. Neuro Report 10:1803-1806 (C) 1999 Lippincott Williams & Wilkins.