Zinc-Induced Inhibition of Insulin Secretion from Isolated Rat Islets of Langerhans

The present experiments indicate that ZnCl₂ (0.015–0.50 mM) inhibits in a dose-dependent manner insulin secretion from isolated rat islets stimulated by D-glucose, L-leucine, and potassium. This inhibitory effect is partially reversed by washing and antagonized by high calcium concentrations in the medium. Zinc levels that inhibit insulin release do not affect ⁴⁵calcium uptake, and zinc will not replace calcium in triggering insulin release. The conversion of ¹⁴C-D-glucose to ¹⁴CO₂ by islets is not modified by zinc (0.12 mM or 0.50 mM) following either 2- or 0.5-h incubation periods, respectively. It is concluded that the inhibitory effect of zinc on insulin secretion may, in part, be mediated through interference with an intracellular function of calcium by the β-cell.