A new model for transmitter mobilization in the frog neuromuscular junction

The detubulated neuromuscular preparation was stimulated by several thousand stimuli at the rate of 10-20 Hz. During the stimulation there was an exponential decay in transmitter release from the presynaptic terminal. The fraction of the existing store of quanta released by a single pulse was about 0.001. This value is two orders of magnitude smaller than that obtained from short tetanic trains. The discrepancy was attributed to the process of mobilization which sets in during prolonged stimulation of the synapse. A simple analysis shows that the amount of transmitter mobilized after each nerve impulse is a constant fraction of the existing store of quanta.