AMPA receptor-mediated EPSCs in rat neocortical layer II/III interneurons have rapid kinetics.
The properties of spontaneous and miniature (m) AMPA receptor-mediated excitatory postsynaptic currents (EPSCs) were studied in rat neocortical layer II/III fast spiking interneurons. Under optimal recording conditions, averaged mEPSCs had a 10-90% rise time of about 0.3 ms. The decay of averaged mEPSCs was double exponential with time constants of about 1 and 4 ms. Kinetics were observed to slow as series resistance increased. The amplitudes of mEPSCs were much smaller at +50 mV than at -50 mV indicating that the currents were inwardly rectifying. These results suggest that synaptic AMPA receptors on neocortical inhibitory interneurons have a deactivation time constant less than 1 ms which largely determines the decay of the synaptic currents. The receptors appear to lack GluR-2 subunits and may be Ca2+ permeable.
Zhou
F M
FM
Department of Neurobiology, University of Alabama at Birmingham, 35294, USA. zhou@nrc.uab.edu
Hablitz
J J
JJ
D000818:Animals; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D007395:Interneurons / Q000502:physiology*; D007700:Kinetics; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology*
D018091:Receptors, AMPA