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

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Abstract
The effects of Ni2+ 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, Ni2+ 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 Ni2+ does not arise through an effect on energy metabolism or cyclic AMP metabolism. It is concluded that although some effects of Ni2+ may involve antagonism between Ni2+ and Ca2+ in stimulus–secretion coupling, others appear to be independent of Ca2+. It is suggested that Ni2+ may block exocytosis by interfering with either secretory-granule migration or membrane fusion and microvillus formation. The possible mode of action of Ni2+ and its potential use as a tool in the study of exocytosis are discussed.