Uptake and intracellular distribution of labile and total Zn(II) in C6 ratglioma cells investigated with fluorescent probes and atomic absorption

The uptake, intracellular distribution and cytotoxicity of high doses of ex tracellular zinc was investigated in C6 rat glioma cells. Net zinc uptake o ccurred only above certain thresholds in time and concentration, below them no alterations of the intracellular zinc level were observed. These result s were obtained by measurements with the fluorescent dye Zinquin and by ato mic absorption spectrometry, yielding similar results with both methods. Se questration of zinc in intracellular vesicles was observed by fluorescence microscopy. A protective effect of vesicular sequestration is indicated, be cause increased levels of intracellular zinc located in vesicles did not ne cessarily lead to an increase in cytotoxicity. We were able to show that in C6 cells, in contrast to other cell lines, zinc that is released from prot eins by the NO donor SNOC is also sequestered in vesicular structures. Thes e zinc-carrying vesicles showed to be constitutive and are assumed to have a function in the maintainance of the cytosolic content of Zn2+ ions.