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

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.