Presynaptic calcium dynamics at neuromuscular junction (Stockbridge, Moore 1984)

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Accession:9888
The diffusion of calcium is effectively reduced by the ratio of bound to free calcium. Treating the release magnitude as proportional to the fourth power of calcium concentration next to the membrane gives reasonable facilitation with very little release between spikes.
Reference:
1 . Stockbridge N, Moore JW (1984) Dynamics of intracellular calcium and its possible relationship to phasic transmitter release and facilitation at the frog neuromuscular junction. J Neurosci 4:803-11 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuromuscular Junction;
Brain Region(s)/Organism:
Cell Type(s):
Channel(s):
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Simplified Models; Short-term Synaptic Plasticity; Facilitation; Calcium dynamics;
Implementer(s): Hines, Michael [Michael.Hines at Yale.edu];
Stockbridge and Moore. (1984) Dynamics of intracellular calcium and its possible
relationship to phasic transmitter release and facilitation at the frog
neuromuscular junction.
J. Neurosci. 4: 803-811

The model semiquantitatively reproduces figures 2-6. Slight
discrepancies are due to the radial spatial discretization process. In
this model, the second order correct calcium concentrations are located at
i*100 angstroms from the cylindrical membrane. i.e. the 0th compartment
is membrane adjacent instead of at 50Angstroms and has half the volume
of other compartments. The NANN-1 th compartment contains the remainder of
the cell volume. Values for the pump magnitudes (ke in cm/sec) are multiplied
by the (1+beta) factor for consistency with the paper. It was not made clear
in the paper that although (1+beta) can be considered a scale factor for the
diffusion constant, in that interpretation it must also scale source and sink fluxes.
Apparently only the source flux was scaled.

The NEURON implementation of this model was prepared by Michael Hines.
Questions about details of this implementation should be addressed to him
at michael.hines@yale.edu.


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