Ryanodine receptor-transmitter release site coupling increases quantal size in a synapse-specific manner.
The mechanisms by which presynaptic neurones differentially regulate synaptic transmission with multiple postsynaptic targets in the brain are not fully understood. Using intracellular sharp electrode and whole-cell voltage-clamp recordings of soma-soma synapses between identified Lymnaea neurones, we provide direct evidence that quantal size is regulated presynaptically through the coupling of multiple release sites. This coupling effectively multiplies quantal size, thereby providing significant influence over parameters of synaptic transmission that are influenced by quantal size, such as the variance in transmitter release at stationary release probabilities. Variation in the degree of coupling is dependent on the identity of the postsynaptic cell, even though the variation in quantal size is of presynaptic origin. We have therefore demonstrated the presence of a novel mechanism by which presynaptic neurones may differentially regulate quantal size at select synaptic connections, in turn providing them with a means of regulating synaptic transmission with multiple postsynaptic cells.
Dunn
Tyler W
TW
Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, 3330 Hospital Drive, NW, Calgary, Alberta T2N4N1, Canada.
Syed
Naweed I
NI
D000818:Animals; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008954:Models, Biological; D009474:Neurons / Q000166:cytology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques / Q000379:methods; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology*; D012908:Snails; D013569:Synapses / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D018377:Neurotransmitter Agents; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine