Facilitation of transmitter release through available transmitter regulation. An explanation not involving residual calcium theory.

A mathematical model of synaptic transmission at the neuromuscular junction is used to reproduce the differential effect of stimulation frequency on the growth of facilitation as well as the two components of facilitation identified by Mallart and Martin. Computer simulations based on this model show that the influence of an active calcium residue accumulating inside the nerve terminal is not absolutely necessary to explain the course of facilitation during and following repetitive stimulation. Nevertheless, it is concluded that such a residue remains a very important factor which may exert an influence on the development and control of longer term phenomena such as augmentation and potentiation, the two components of posttetanic potentiation.