The amphicrine pancreatic cell line, AR42J, secretes GABA and amylase by separate regulated pathways.

Treatment of AR42J cells with dexamethasone leads to an enhanced formation of amylase-containing granules and facilitates their regulated secretion. Besides the exocrine properties, AR42J cells possess a specific uptake system for [3H]GABA. The stored GABA can be released upon potassium depolarisation in a Ca(2+)-dependent manner. After treatment with dexamethasone, potassium depolarisation fails to release GABA, but instead causes a Ca(2+)-dependent secretion of amylase. Since vesicles similar to small synaptic vesicles of neurons have been identified in AR42J cells, we suggest that the regulated GABA release is mediated by this vesicle type. It is tentatively speculated that other epithelial cells, which also contain small synaptic vesicles and amino acid neurotransmitters, may release them in a similar fashion.