Influence of depolarizing pulse duration on the time course of transmitter release in lobster.

1. Experiments have been made at lobster neuromuscular synapses to study synaptic delays and in particular the phenomenon known as 'latency shift'. Earlier work had suggested that synaptic delay becomes prolonged when pulses of long duration are applied to presynaptic terminals. 2. By observing single quanta, prolonged depolarizing pulses at low and moderate amplitudes have been shown to shift the peak of the synaptic delay histogram. There is however no increase in the minimal delay. 3. The apparent differences between these and earlier results have been shown to depend on differences in experimental procedures. In particular, in the present study equal numbers of pulses are applied at the various pulse durations and the number of quanta that had been released is presented.