Ca2+ dependence of the release of noradrenaline during nerve degeneration in the parotid gland.

Amylase secretion "in vitro" was used as an indication of the degeneration activity of sympathetically denervated parotid glands. Seventeen and a half hours after sympathetic denervation, slices of parotid gland released amylase into the incubation medium at a rate higher than that observed for non-denervated glands. The time course of amylase release from denervated glands followed a bell-shaped pattern similar to that observed in other denervated structures. Lowering extracellular Ca2+ to 0.25 mmol/l diminished significantly the release of amylase. Low Ca2+ however, did not decrease the amylase release in response to added noradrenaline. These results indicate that Ca2+ is required for the release of noradrenaline from degenerating nerve endings.