An electrophysiological study of the storage, synthesis and release of acetylcholine from an identifiable inhibitory synapse in the brain of Helix aspersa

Abstract

Intracellular recordings have been made from a single identifiable neurone in the suboesophageal ganglionic mass of Helix aspersa. This cell has an inhibitory cholinergic synapse, with an inhibitory postsynaptic potential (IPSP) of 14–20 mV amplitude. Following repetitive stimulation the amplitude declines to a constant level of 4–6 mV. The results from repetitive stimulation experiments at different frequencies suggest that acetylcholine is released from a single presynaptic store. Repetitive stimulation either in the presence of hemicholinium or in snails pretreated with hemicholinium results in the almost complete disappearance of the IPSP. It is suggested that the release of acetylcholine is exponential and that hemicholinium blocks acetylcholine resyn thesis.