Reversible stabilization of liver lysosomes by zinc ions

The effect of zinc ions on the stability of rat liver lysosomes was studied. Zinc was added by several methods: feeding the animals a high-zinc diet; infusion of zinc into the liver through the portal vein, or by adding zinc to the lysosomal fraction either before or after isolation of this fraction from rat liver homogenates. By all techniques, addition of zinc reduced the release of beta-glucuronidase from liver lysosomes. Lysosomes and lysosomal membranes from rats fed a high-zinc diet were found to be relatively high in zinc. These lysosomes were less fragile than lysosomes from the liver of control animals. The stabilizing effect of zinc ions could be reversed by treatment of lysosomes with phosphate buffer. We concluded that increasing the zinc content in the liver by any of these methods results in stabilization of liver lysosomes.