Assessment of the intracellular distribution of copper in liver specimens from cats

The intracellular distribution of copper in the liver has been investigated in dogs and humans. However, this has not been reported in cats. This study aimed to assess the intracellular copper distribution in liver specimens from cats with a range of hepatic copper concentrations. Twenty-nine frozen liver specimens from cats were included. Each liver specimen was divided into two pieces for overall copper quantification and tissue fractionation. The copper concentrations in liver specimens and liver fractions were measured by flame atomic absorption spectroscopy. Five specimens had copper concentrations < 100 μg/g dry weight, eight had copper concentrations between 100 and 180 μg/g, 14 had copper concentrations between 181 and 700 μg/g, and two had copper concentrations >700 μg/g. Only one specimen had positive copper staining. Regardless of the overall concentrations, copper was mostly found in the cytosolic fraction followed by the nuclear, large granule, and microsomal fractions. Our findings indicate that similarly to other species, intracellular copper is predominantly found in the cytosolic and nuclear fractions in cats. The distribution in cats with copper-loaded conditions, such as primary copper hepatopathy, was not assessed but warrants evaluation.