Hypoosmolarity and ammonia induce zinc liberation in cultured rat astrocytes

Zinc deficiency may play a role in the development of hepatic encephalopathy (HE). To clarify effects of ammonia and hypoosmolarity on astroglial zinc homeostasis, the zinc sensitive fluorescence dyes Zinquine and Newport-green were used. Ammonia (5 mmol/L) and hypoosmolarity (205 mosmol/L) induced astrocyte swelling led to a pronounced increase of Zinquine and Newport-green fluorescence suggestive for an intracellular elevation of zinc [Zn2+]i. This response was linked to ammonia and hypoosmotic induced oxidative/nitrosative stress and could be prevented by the antioxidant epigallocatechin-gallate (30µmol/L), b…