Ultra-fast versus sustained cholinergic transmission: a variety of different mechanisms.
Although synaptic transmission was assumed to use the same mechanisms in the case of different synapses of the central and peripheral nervous system, recent research revealed a great variety of different processes. Time might be a crucial factor to be considered in this diversity. It is recalled that the speed of a chemical reaction is inversely related to affinity. "Time is gained at the expense of sensitivity" as noticed by Bernard Katz (1989). Therefore, synaptic transmission will occur at a high speed only if it is supported by low affinity reactions. In the present work, we compare two examples of ultra-rapid transmission (the Torpedo nerve electroplaque synapse and the rat hippocampus mossy fiber/CA3 synapses), with a cholinergic process operating with high affinity but at a low speed: the release of glutamate elicited by nicotine from mossy fibers of the rat hippocampus.
Neurosciences Fondamentales, University of Geneva, CMU, 1211 Geneva-4, Switzerland. Yves.Dunant@unige.ch
Yves
Y
Dunant
Victor
V
Bancila
Miguel
M
Cordeiro
D000818:Animals; D002490:Central Nervous System / Q000502:physiology* / Q000648:ultrastructure; D004557:Electric Organ / Q000502:physiology* / Q000648:ultrastructure; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D019599:Mossy Fibers, Hippocampal / Q000502:physiology* / Q000648:ultrastructure; D018722:Nicotinic Agonists / Q000494:pharmacology; D017933:Peripheral Nervous System / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018722:Nicotinic Agonists; D018698:Glutamic Acid