Mechanism of Transmitter Release: Voltage Hypothesis and Calcium Hypothesis

Abstract
The calcium hypothesis of synaptic transmission has been challenged by experimental results using the crayfish neuromuscular junction that suggest that presynaptic depolarization can trigger transmitter release directly without calcium influx. Results from electrophysiological experiments using the same preparation do not support this voltage hypothesis, but are consistent with the calcium hypothesis. Voltage may modulate, but not elicit, transmitter release.