Multivesicular release at climbing fiber-Purkinje cell synapses.
Synapses driven by action potentials are thought to release transmitter in an all-or-none fashion; either one synaptic vesicle undergoes exocytosis, or there is no release. We have estimated the glutamate concentration transient at climbing fiber synapses on Purkinje cells by measuring the inhibition of excitatory postsynaptic currents (EPSCs) produced by a low-affinity competitive antagonist of AMPA receptors, gamma-DGG. The results, together with simulations using a kinetic model of the AMPA receptor, suggest that the peak glutamate concentration at this synapse is dependent on release probability but is not affected by pooling of transmitter released from neighboring synapses. We propose that the mechanism responsible for the elevated glutamate concentration at this synapse is the simultaneous release of multiple vesicles per site.
Wadiche
J I
JI
Vollum Institute, Oregon Health Sciences University L474, 3181 S. W. Sam Jackson Park Road, Portland, OR 97201, USA.
Jahr
C E
CE
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018698:Glutamic Acid / Q000032:analysis / Q000378:metabolism; D007700:Kinetics; D007736:Kynurenic Acid / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011689:Purkinje Cells / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000502:physiology; D013569:Synapses / Q000737:chemistry / Q000502:physiology*; D009435:Synaptic Transmission
D004151:Dipeptides; D018377:Neurotransmitter Agents; D011810:Quinoxalines; D018091:Receptors, AMPA; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C028929:gamma-glutamylglycine; D018698:Glutamic Acid; D007736:Kynurenic Acid; D002118:Calcium