Slow deactivation kinetics of NMDA receptors containing NR1 and NR2D subunits in rat cerebellar Purkinje cells.
We have examined the deactivation kinetics of native N-methyl-D-aspartate receptors (NMDARs) containing NR1 and NR2D subunits by patch-clamp recording from Purkinje cells in cerebellar slices from young rats. NMDAR-mediated whole-cell currents were elicited in response to bath application of 20 microM NMDA and 50 microM glycine. The NMDAR-mediated currents were small, with an average whole-cell conductance of approximately 750 pS. Following the rapid application of brief pulses (1-10 ms) of 1 mM glutamate to outside-out membrane patches, we observed a low-conductance type of single-channel activity which lasted up to 30 s after the removal of agonist. Analysis of individual channel openings revealed asymmetry of transitions between the main- and subconductance states - a characteristic of NR1/NR2D-containing NMDARs. The averaged macroscopic current exhibited a decay time course which was well described by a single exponential function with a time constant of approximately 3 s. We conclude that native NR1/NR2D-containing NMDARs, like their recombinant counterparts, display very slow deactivation kinetics. This feature should provide a means for identification of these receptors at synapses, and indicates that they do not contribute to the synaptic NMDAR currents so far described.
Misra
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C
Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
Brickley
S G
SG
Wyllie
D J
DJ
Cull-Candy
S G
SG
D000818:Animals; D018698:Glutamic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D018408:Patch-Clamp Techniques; D011689:Purkinje Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism
C409466:NR1 NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid