Three stages of copper accumulation in hepatocellular lysosomes: X-ray microanalysis of copper-loaded golden hamsters.

Male golden hamsters were loaded with copper by supplying them for up to 12 weeks with drinking water containing 0.5% cupric acetate. The copper feeding increased hepatic copper to widely varying levels. Energy dispersive X-ray microanalysis could always identify a copper-sulphur complex in the hepatocyte lysosomes of copper-loaded hamsters and the X-ray intensity of copper was found to be a reliable parameter to measure in-situ copper accumulation. Combining this parameter with the copper binding ratio expressed by delta Cu/delta S enabled us to discern two stages of sub-histochemical copper accumulation. The first stage was marked by low levels of both lysosomal copper and binding ratio, which suggested that this initial copper transfer was mediated by unsaturated cuproproteins. The second stage was characterized by median amounts of lysosomal copper and a binding ratio of more than 0.50. At the third stage, histochemically detectable copper appeared in animals whose lysosomal copper was extraordinarily high in later experimental periods. With the copper binding ratio being in the same range of 0.50-0.83, it seemed that saturated cuproproteins were the main mediator of copper transport in the later two stages.