[Mechanism of facilitated transmitter release in the neuromuscular synapse]

In the frog m. sartorius preparation, the intracellular recording at large concentrations of Ca2+ ions revealed two components in the facilitation following a single stimulus applied to the motor nerve. A decrease in the [Ca0] concentration led to appearance of an additional very early component of the facilitation. Extracellular recording always revealed all three components. In rhythmical stimulation, the early facilitation component is summed up according to the power model of facilitation summation with the power index 2 to 5 depending on initial probability of a quantum transmitter release. The first and the second components are summed up according to the linear facilitation model.