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.
Model Type: Neuromuscular Junction
Simulation Environment: NEURON
Implementer(s): Hines, Michael [Michael.Hines at Yale.edu]
Stockbridge N, Moore JW. (1984). Dynamics of intracellular calcium and its possible relationship to phasic transmitter release and facilitation at the frog neuromuscular junction. The Journal of neuroscience : the official journal of the Society for Neuroscience. 4 [PubMed]