Calcium influx following onset of electrical afterdischarge is not required for hormone secretion from neuroendocrine cells of Aplysia.

The neuroendocrine bag cells are an attractive model system for investigating cellular mechanisms mediating the effects of membrane excitability on hormone secretion because of the ability to easily monitor their electrical and secretory functions simultaneously. We investigated the role of extracellular calcium in regulating prolonged release of egg-laying hormone from bag cells following stimulation of an electrical afterdischarge. We report that calcium influx is required for initiation of the afterdischarge, but is not required for prolonged hormone secretion once the afterdischarge has been triggered.