The effect of nickel on secretory systems. Studies on the release of amylase, insulin and growth hormone.

The effects of Ni(2+) on the release of amylase from rat parotids, insulin from mouse pancreatic islets and growth hormone from bovine pituitary slices were investigated. In all these secretory systems, Ni(2+) was shown to inhibit release evoked by a variety of stimuli both physiological and pharmacological. Measurements of rates of substrate oxidation and tissue concentrations of ATP and 3':5'-cyclic AMP suggest that this inhibitory action of Ni(2+) does not arise through an effect on energy metabolism or cyclic AMP metabolism. It is concluded that although some effects of Ni(2+) may involve antagonism between Ni(2+) and Ca(2+) in stimulus-secretion coupling, others appear to be independent of Ca(2+). It is suggested that Ni(2+) may block exocytosis by interfering with either secretory-granule migration or membrane fusion and microvillus formation. The possible mode of action of Ni(2+) and its potential use as a tool in the study of exocytosis are discussed.