Neurons communicate using electrical activity, but the exchange of information between neurons usually requires the release of chemical messengers. This fast synaptic transmission is tightly regulated by the flux of calcium ions into specialized active zone regions of the presynaptic neuron. The magnitude, timing, and spatial distribution of calcium influx determine the amount of transmitter that is released. We propose to use high speed imaging at the frog neuromuscular junction to increase our understanding of the spatial distribution of the calcium influx profiles that regulate release at this synapse. The frog neuromuscular junction is a classic synaptic preparation with large and well-organized active zones. As such, this preparation combines a spatial organization that is favorable for calcium imaging at the level of single active zones with a wealth of background information related to the physiology and anatomy of this synapse. We propose to characterize with fast temporal resolution the spatial distribution of calcium influx along the length of the neuromuscular junction. We will test the hypothesis that the opening of a single Ca2+ channel generates a stimulus-evoked Ca2+ entry site and that single channel openings trigger transmitter release in the frog neuromuscular junction. In addition, we are interested in studying the effects of G protein modulation of calcium influx through voltage-gated channels at this synapse. These studies will increase our understanding of transmitter release and its modulation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS043396-04
Application #
6997817
Study Section
Special Emphasis Panel (ZRG1-MDCN-4 (01))
Program Officer
Talley, Edmund M
Project Start
2002-12-01
Project End
2007-11-30
Budget Start
2005-12-01
Budget End
2006-11-30
Support Year
4
Fiscal Year
2006
Total Cost
$208,074
Indirect Cost
Name
University of Pittsburgh
Department
Neurology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Luo, Fujun; Dittrich, Markus; Cho, Soyoun et al. (2015) Transmitter release is evoked with low probability predominately by calcium flux through single channel openings at the frog neuromuscular junction. J Neurophysiol 113:2480-9
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Meunier, Frederic A; Nguyen, Tam H; Colasante, Cesare et al. (2010) Sustained synaptic-vesicle recycling by bulk endocytosis contributes to the maintenance of high-rate neurotransmitter release stimulated by glycerotoxin. J Cell Sci 123:1131-40
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Keith, Ryan K; Poage, Robert E; Yokoyama, Charles T et al. (2007) Bidirectional modulation of transmitter release by calcium channel/syntaxin interactions in vivo. J Neurosci 27:265-9
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Wachman, Elliot S; Poage, Robert E; Stiles, Joel R et al. (2004) Spatial Distribution of Calcium Entry Evoked by Single Action Potentials within the Presynaptic Active Zone. J Neurosci 24:2877-85